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Journal articles on the topic 'Motion resistances'
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1
Velescu, C., and N. C. Popa. "Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve." Scientific World Journal 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/649098.
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We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids’ motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i) velocity and pressure distributions, (ii) average velocity, (iii) volume flow rate of the liquid, (iv) pressures difference, and (v) radial clearance.
2
Gładysiewicz, Lech, and Martyna Konieczna. "Theoretical analysis of the impact of belt speed on indentation rolling resistance." E3S Web of Conferences 71 (2018): 00004. http://dx.doi.org/10.1051/e3sconf/20187100004.
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Belt conveyors, having high reliability and efficiency, are the main means of continuous transportation both in underground and in open-cast mining. Despite their numerous advantages, however, belt conveyors are expensive in maintenance. Therefore, improvements in the field of belt conveyor transportation largely focus on methods for lowering their power consumption. The energy consumption level of a belt conveyor depends on the motion resistances which occur during its operation. In the case of conveyors having lengths greater than 80 m, main resistances are the dominant component of motion resistances, and up to 60% of main resistances may be accounted for by the rolling resistances of the belt on idlers. Motion resistances, including rolling resistances, have long remained an object of research. Extensive laboratory tests and increasingly detailed theoretical models allow a better insight into the phenomena involved in the movement of the belt on the conveyor. Different research results place different weight on the influence of individual parameters (such as unit load or phase lag angle) on belt rolling resistance. The greatest inconsistencies, however, are observed in the analyses of belt speed impact, which is occasionally not even included in some models. This paper discusses the known and commonly used methods for determining the rolling resistances of the belt on idlers. It also proposes a new solution, which employs the analysis of strain variation in the belt for successive load cycles to determine whether belt speed has a direct influence on the value of rolling resistance.
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Waskito, Kurniawan Teguh, and Yanuar. "On the High-Performance Hydrodynamics Design of a Trimaran Fishing Vessel." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, no. 1 (June 3, 2021): 17–33. http://dx.doi.org/10.37934/arfmts.83.1.1733.
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Trimaran hull form as multihull ship becomes more attractive these days in various ship types. It offers more advantages in terms of seakeeping performances, particularly on the application of a fishing vessel. However, thus far, the conventional design of fishing vessels is not favorable to ensure the safety of a vessel sailing in a rough sea. In conjunction with such issues, we discuss a trimaran fishing vessel design based on the seakeeping criterion to evaluate the dynamic stability, ship motion RAOs, and ship resistances at the initial design stages using linear strip theory. The intact stabilities are calculated to complement the seakeeping results. The analytical method based on the slender body method is used to evaluate the steady wave resistances. The results of heave, pitch, roll motions, and the ship resistances are discussed. At the zero speed and forward speed, the trimaran shows a favorable motion amplitude, although in forward speeds at the case of head seas there is no significant difference. The trimaran presents a favorable steady-resistance up to the ship speed of Fn=0.27, and it becomes deteriorating than the monohull at higher ship speeds. However, the added wave resistances of the wavelength range 1.0 – 3.0 shows significant added resistances at Fn=0.25 and Fn=0.35, respectively. The results of this study present promising seakeeping and resistance characteristics of the trimaran hull form. The trimaran hull form ensures the safety, reliability, and operation efficiency of ships sailing in broader ranges of violent-sea environment.
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Ke, Nan, Hu-Tian Feng, Zeng-Tao Chen, Yi Ou, and Chang-Guang Zhou. "Real contact total length of linear motion roller guide without preload based on Greenwood–Williamson rough contact model." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 22 (August 10, 2016): 4274–84. http://dx.doi.org/10.1177/0954406216664548.
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In traditional studies of linear motion roller guide, the static stiffness is a main indicator to evaluate the mechanical behavior. However, the local contact profile between the roller and raceway surface, although very important to the precision maintenance, cannot be reflected in the measured value of static stiffness. In this article, a new indicator, named the real contact total length (RCTL), is proposed based on the Greenwood–Williamson model and the Hertz contact theory. In particular, an electric contact model is presented where the RCTL of linear motion roller guide without preload is expressed in terms of the measured electric resistances. To verify the model, an experiment is conducted to measure the electric resistances under different vertical loads by a designed load test bench and a digital, direct-current, high-resolution electric resistance meter (DRRM). The test results show good agreement with the model. Based on the electric contact model, the main parameters that affect the RCTL value are roughness Ra and the length of roller, which are directly related to the mechanical behavior of linear motion roller guide in the design and manufacture stages.
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Hirawatari, Sueji, Hisaki Watari, Shinichi Nishida, Yuki Sato, and Mayumi Suzuki. "Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test." Materials Science Forum 889 (March 2017): 119–26. http://dx.doi.org/10.4028/www.scientific.net/msf.889.119.
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This paper deals with friction properties and deformation resistance during hot forming of Mg-Al-Ca-Mn series magnesium alloys. Friction coefficients between dies and magnesium alloys were obtained by ring compression tests that used graphite, PTFE, and an oil lubricant in a hot-forging process. Hot forging was performed under various conditions to clarify the effects of types of lubricants and slide motion of the press machines on friction properties. Two types of slide motion, a constant velocity motion and a pulse motion were selected in the ring-compression test. It was found that graphite with an oil lubricant effectively eliminated die sticking in hot forming of magnesium alloys. The isothermal deformation resistances were derived using friction coefficients obtained by ring-compression tests as well as finite-element simulations. The predicted stress strain curves with temperature were examined with the stress-strain relationship obtained in experiments using a servo press and demonstrated the effectiveness of the proposed method.
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Shao, Nan, Jijian Lian, Guobin Xu, Fang Liu, Heng Deng, Quanchao Ren, and Xiang Yan. "Experimental Investigation of Flow-Induced Motion and Energy Conversion of a T-Section Prism." Energies 11, no. 8 (August 6, 2018): 2035. http://dx.doi.org/10.3390/en11082035.
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Flow-induced motion (FIM) performs well in energy conversion but has been barely investigated, particularly for prisms with sharp sections. Previous studies have proven that T-section prisms that undergo galloping branches with high amplitude are beneficial to energy conversions. The FIM experimental setup designed by Tianjin University (TJU) was improved to conduct a series of FIM responses and energy conversion tests on a T-section prism. Experimental results are presented and discussed, to reveal the complete FIM responses and power generation characteristics of the T-section prism under different load resistances and section aspect ratios. The main findings are summarized as follows. (1) Hard galloping (HG), soft galloping (SG), and critical galloping (CG) can be observed by varying load resistances. When the load resistances are low, HG occurs; otherwise, SG occurs. (2) In the galloping branch, the highest amplitude and the most stable oscillation cause high-quality electrical energy production by the generator. Therefore, the galloping branch is the best branch for harvesting energy. (3) In the galloping branch, as the load resistances decrease, the active power continually increases until the prism is suppressed from galloping to a vortex-induced vibration (VIV) lower branch with a maximum active power Pharn of 21.23 W and a maximum ηout of 20.2%. (4) Different section aspect ratios (α) can significantly influence the FIM responses and energy conversions of the T-section prism. For small aspect ratios, galloping is hardly observed in the complete responses, but the power generation efficiency (ηout,0.8 = 27.44%) becomes larger in the galloping branch.
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Gallena, Sally J. K., Nancy Pearl Solomon, Arthur T. Johnson, Jafar Vossoughi, and Wei Tian. "The Effect of Exercise on Respiratory Resistance in Athletes With and Without Paradoxical Vocal Fold Motion Disorder." American Journal of Speech-Language Pathology 24, no. 3 (August 2015): 470–79. http://dx.doi.org/10.1044/2015_ajslp-14-0110.
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Purpose An investigational, portable instrument was used to assess inspiratory (R i ) and expiratory (R e ) resistances during resting tidal breathing (RTB), postexercise breathing (PEB), and recovery breathing (RB) in athletes with and without paradoxical vocal fold motion disorder (PVFMD). Method Prospective, controlled, repeated measures within-subject and between-groups design. Twenty-four teenage female athletes, 12 with and 12 without PVFMD, breathed into the Airflow Perturbation Device for baseline measures of respiratory resistance and for two successive 1-min trials after treadmill running for up to 12 min. Exercise duration and dyspnea ratings were collected and compared across groups. Results Athletes with PVFMD had lower than control R i and R e values during RTB that significantly increased at PEB and decreased during RB. Control athletes' R e decreased significantly from RTB to PEB but not from PEB to RB, whereas R i did not change from RTB to PEB but decreased from PEB to RB. Athletes without PVFMD ran longer, providing lower dyspnea ratings. Conclusion Immediately following exercise, athletes with PVFMD experienced increased respiratory resistance that affected their exercise performance. The difference in resting respiratory resistances between groups is intriguing and could point to anatomical differences or neural adaptation in teenagers with PVFMD. The Airflow Perturbation Device appears to be a clinically feasible tool that can provide insight into PVFMD and objective data for tracking treatment progress.
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Kim, Yonghwan, Dong-Min Park, Jae-Hoon Lee, Jaehoon Lee, Byung-Soo Kim, Kyung-Kyu Yang, Semyun Oh, and Dong-Yeon Lee. "Numerical Analysis and Experimental Validation of Added Resistance on Ship in Waves." Journal of Ship Research 63, no. 4 (December 1, 2019): 268–82. http://dx.doi.org/10.5957/josr.10180091.
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In this study, the added resistance of a liquefied natural gas carrier (LNGC) in the presence of waves is studied experimentally and numerically.The ship model is an LNGC designed by Samsung Heavy Industries (SHI). Experiments on ship motion responses and added resistance under head sea conditions were conducted at the Seoul National University and SHI. The influences of the experimental methods (captive and self-propulsion methods), incident wave amplitude, and regular and irregular wave conditions on the added resistance are evaluated using the same model ship set at different scales. In the numerical studies, the motion responses and added resistance are obtained using three methods—the strip method by adopting momentum conservation; Rankine panel method using pressure integration; and computational fluid dynamics method, using the difference in the resistances in waves and calm water. The experimental and numerical results under various conditions are compared, and the characteristics of the experimental and numerical results are discussed.
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Crăciun, Camil, and Cătălin Cruceanu. "Influence of resistance to motion of railway vehicles on the longitudinal trains dynamics." MATEC Web of Conferences 178 (2018): 06003. http://dx.doi.org/10.1051/matecconf/201817806003.
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Longitudinal dynamics of trains is a subject that generates discussions and views on the parameters that interfere and influence both the size of the forces and their distribution in the train body. The paper is a study to determine the influence of resistances to motion on the longitudinal dynamic forces that develop in the body of the train in the braking process. For this, a train study model of ten identical vehicles, to which the locomotive may or may not be attached, is adopted. Initially, the simulation program for the non-locomotive model is run in two variants: with and without introducing additional resistances to motion, followed by the same simulations but with the locomotive introduced and a wagon removed, thus the number of vehicles remains the same for all the cases presented.
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Ianăşi, Aurora Cătălina, and Nicoleta Maria Mihuţ. "Mechanical and Geometrical Characterization of the Conveyors Belts from Mineral Resources Exploitation." Advanced Materials Research 837 (November 2013): 99–104. http://dx.doi.org/10.4028/www.scientific.net/amr.837.99.
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Conveyor belt is one of the most common types of continuous handling equipment used for moving rocks of various sizes horizontally or inclined. From researches done in the exploitation of mineral resources and rocks and from the Strength of Materials calculations in this paper is observed above the conveyor sizing and other elements of the transporter requires knowing how belt traction forces (tensions thereof) varies on the conveyor length. In all cases the operation of the conveyor belt must be provided without engaging the slip phenomenon and limiting its displacement (between sets of rollers) so conveyor can operating at optimum parameters. The materials that make up a conveyor belt can be divided into two categories: materials for coating plates or outer shell and a resistance part, areas with inserts that can be textile and steel cables. Because the bands are subjected to tensile efforts and wear phenomena we determine the maximum strength they can operate without going into permanent deformation regime. Conveyor belt dimensioning calculations and other elements of a conveyor varies depending on its length and the carrier operating situations. We can see, also, that sizing conveyor belt and other conveyor components require knowledge of how belt traction forces (tensions thereof) varies along the length of the conveyor. The tensions from the conveyor belt will be study for the climb section and for the descend section. It mentions that the specific resistance to motion of the belt on full branch, consisting of resistances due: current material deformation, rotation rollers camps because pressing rubber layer and roll belt and belt bending. Since current material strength due to deformation and bending belt represents a large percentage of total specific resistance to motion, it follows that resistance decreases with decreasing displacement belt between rollers and increase with the effort in belt, respectively. This explains that resistance decreases with increasing length of conveyor (especially when its initial stretch is great), and with increasing conveyor tilt too. Also, we observe, from the values of forces calculated in the paper, that the resistance to rotation of the roller bearings decreases with increasing load on the roll, hence the values adopted for specific resistance to movement can be more larger on the empty branch than on the full. Knowing how to calculate resistances to motion of the belt, you can fix that occur belt efforts through the points made on the contour method, starting point of the drum motor development and ending point of winding it. These movement resistances calculated for empty and full branches are needed to precisely determine the installed power of the conveyor belt.
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Chen, Yumiao, and Zhongliang Yang. "GEP-based predictive modeling of breathing resistances of wearing respirators on human body via sEMG and RSP sensors." Sensor Review 39, no. 4 (July 15, 2019): 439–48. http://dx.doi.org/10.1108/sr-08-2018-0210.
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PurposeBreathing resistance is the main factor that influences the wearing comfort of respirators. This paper aims to demonstrate the feasibility of using the gene expression programming (GEP) for the purpose of predicting subjective perceptions of breathing resistances of wearing respirators via surface electromyography (sEMG) and respiratory signals (RSP) sensors.Design/methodology/approachThe authors developed a physiological signal monitoring system with a specific garment. The inputs included seven physical measures extracted from (RSP) and (sEMG) signals. The output was the subjective index of breathing resistances of wearing respirators derived from the category partitioning-100 scale with proven levels of reliability and validity. The prediction model was developed and validated using data collected from 30 subjects and 24 test combinations (12 respirator conditions × 2 motion conditions). The subjects evaluated 24 conditions of breathing resistances in repeated measures fashion.FindingsThe results show that the GEP model can provide good prediction performance (R2= 0.71, RMSE = 0.11). This study demonstrates that subjective perceptions of breathing resistance of wearing respirators on the human body can be predicted using the GEP via sEMG and RSP in real-time, at little cost, non-invasively and automatically.Originality/valueThis is the first paper suggesting that subjective perceptions of subjective breathing resistances can be predicted from sEMG and RSP sensors using a GEP model, which will remain helpful to the scientific community to start further human-centered research work and product development using wearable biosensors and evolutionary algorithms.
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Yeo, Na Eun, Doo-In Kim, and Myung Yung Jeong. "Compressive and Shear Resistances of Confined Water Droplet in Sliding Motion Against Hydrophobic Counterpart." Science of Advanced Materials 12, no. 4 (April 1, 2020): 589–93. http://dx.doi.org/10.1166/sam.2020.3671.
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The compressive and shear resistances of the water droplet confined between the hydrophobic surfaces were investigated to evaluate the effect of the micro-scale surface pattern on the repulsive capillary force and friction of droplet. The hydrophobic surfaces covered with square pillar structures in the hexagonal array were prepared and the repulsive normal load and friction coefficient of the droplet were characterized. The force measurements in the vertical and lateral directions on the droplet confined between the prepared hydrophobic surfaces revealed that the compressive resistance to the vertical motion which is identical with the repulsive capillary force increases with deformation when the deformed droplet is horizontally symmetric. On the other hand, the friction coefficient of the squeezed droplet is inversely proportional to the repulsive capillary force. It was found that the reduced pressure acting on the solid–liquid interface results in the abnormal reduction in friction coefficient. In addition, the critical hydraulic pressure analysis confirmed that the partially wetted Cassie-Baxter (CB) state is maintained during sliding motion.
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Meng, Wen Jun, and Wei Peng. "The Design of VI-Based Synthesized Testing System for Belt Conveyors." Advanced Materials Research 97-101 (March 2010): 4367–70. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.4367.
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Because of the resistances to the belt’s motion in belt conveyors mainly caused by friction and frictional wear of the belt being one of key factors to effect its service life, the paper gives a simple qualitative investigation of frictional characteristic of the belt from its material behavior. Using stimulant coefficient of friction, it could make quantitative analysis for the resistances to the belt’s motion caused by friction etc, and design a belt conveyors synthesized testing system, the aim of the system is to test stimulant coefficient of friction under more type conveyors and more operating modes. Measurement and control of the system is based on VI(Virtual Instrument) software——LabVIEW, and in consequence it simplifies the hardware of the system, it also enhances human-computer interaction of the system’s operational interface.
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Salazar, Ryan, Ryan Quintana, and Abdessattar Abdelkefi. "Role of Electromechanical Coupling, Locomotion Type and Damping on the Effectiveness of Fish-Like Robot Energy Harvesters." Energies 14, no. 3 (January 29, 2021): 693. http://dx.doi.org/10.3390/en14030693.
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In this work, an investigation into the influence of prescribed motion on a body caudal fin aquatic unmanned vehicle (AUV) energy harvester is carried out. The undulatory–oscillation locomotion inspired by fishes actuates a composite beam representative of a spinal column with a piezoelectric patch. Two patch configurations—one at the head and tail—are considered for the AUV energy harvester, with a length that would not activate a harmonic in the system. An electromechanical model which accounts for the strain of the prescribed motion and the induced relative strain is developed. Discretizing the relative strain using Galerkin’s method requires a convergence study in which the impacts of the prescribed motion, dependent on the undulation and envelope of the motion, are investigated. The combination of prescribed motion and structural terms leads to a coupling that requires multiple investigations. The removal of the undulation of the system produces a more consistent response. The performances of the two different patch configurations undergoing different prescribed motions are studied in terms of coupled damping and frequency effects. An uncoupled Gauss law-based model is adopted to compare the performance of our approach and that of the coupled electromechanical model harvester. It is demonstrated that there is a complex interaction of the phases of the prescribed and relative motions of the structure which can lead to the development or destruction of the response of the total motion or voltage for the system. The results show that the structural damping and type of locomotion are the most influential parameters on the validity of the uncoupled approach. It is also found that the optimal resistances for the coupled and uncoupled representations are the same for the two motions and patch configurations considered.
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Tomaszewski, Sylwin, and Jerzy Frączek. "Simulation tests of relay valve in the context of its resistances to motion." Rail Vehicles, no. 3 (September 2, 2016): 39–47. http://dx.doi.org/10.53502/rail-138740.
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W artykule przedstawiono opis przekładnika ciśnienia cylindrowego zaprojektowanego i wykonanego przez Instytut Pojazdów Szynowych „TABOR”. Scharakteryzowano poszczególne elementy składowe jego budowy oraz wytypowano te, które mają istotny wpływ na zmianę oporów ruchu przekładnika ciśnienia. Przedstawiono aktualnie obowiązujące kryteria dotyczące parametrów działania przekładnika ciśnienia cylindrowego. Zaprezentowano wybrane wyniki badań, które polegały na ustaleniu wpływu oporów ruchu na zmianę wartości histerezy oraz poprawności działania przekładnika ciśnienia. Pokazano stanowisko, na którym przeprowadzono badania symulacyjne działania przekładnika ciśnienia oraz stanowisko do pomiarów oporów ruchu. W artykule przedstawiono także komputerowy model symulacyjny, w którym weryfikowano wyniki badań.
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Zhou, Li, Feng Diao, Ming Song, Yue Han, and Shifeng Ding. "Calculation Methods of Icebreaking Capability for a Double-Acting Polar Ship." Journal of Marine Science and Engineering 8, no. 3 (March 6, 2020): 179. http://dx.doi.org/10.3390/jmse8030179.
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As a key parameter, icebreaking capability is often used to judge whether a polar ship could navigate in level ice at a certain speed. This paper presents two methods to calculate icebreaking capability. The first one is a static method based on the estimation of ice resistance under different ice thicknesses and ship speeds. The second is a dynamic method that involves solving the equation of motion. A series of model tests with a double-acting icebreaking tanker were also carried out in the ice basin of the Krylov State Research Center to measure ice resistances. The simulated ice resistances were compared with model tests results for both ahead and astern running operations. The calculated icebreaking capability based on static and dynamic methods was validated with the model test result. A good agreement was achieved between measurement and simulation. The discrepancy between the model test result and the result simulated by the static or dynamic method was minor.
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Shao, Nan, Guobin Xu, Fang Liu, Xiang Yan, Xiaoqun Wang, Heng Deng, and Zheng Zheng. "Experimental Study on the Flow-Induced Motion and Hydrokinetic Energy of Two T-section Prisms in Tandem Arrangement." Applied Sciences 10, no. 3 (February 7, 2020): 1136. http://dx.doi.org/10.3390/app10031136.
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The advantageous performance in terms of energy conversion for the flow-induced motion (FIM) of T-section prisms has been experimentally reported recently. In order to further understand the oscillation and energy conversion of multiple T-section prisms, a series of tests of two T-section prisms arranged in tandem with five different spacing ratios (3 ≤ L/D ≤ 15) and seven load resistances (8 Ω ≤ RL ≤ 41 Ω) were conducted. The effects of the spacing ratio and load resistances on energy conversion were discussed. The main conclusions can be summarized as follows. For most tests, the amplitudes of the upstream T-section prism (UTP) and downstream T-section prism (DTP) were both lower than the amplitude of the single T-section prism (STP) due to the mutual interference of the two prisms. Because of the mutual interference, the active powers of UTP and DTP were both less than that of STP, but at some special spacing ratios or load resistances, the mutual interference benefited the energy converted by the two prisms. In the presented tests, the total optimal active power of the upstream T-section prism and downstream T-section prism (UTP + DTP) was 30.12 W, which was 1.5 times that of STP (20.12 W).
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Romanik, Grzegorz, and Janusz Rogula. "Crankshaft seals with reduced frictional resistance." AUTOBUSY – Technika, Eksploatacja, Systemy Transportowe 19, no. 6 (June 30, 2018): 686–90. http://dx.doi.org/10.24136/atest.2018.157.
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The article discusses the cooperation of the elastomeric sealing ring with the shaft in terms of wear and losses to overcome friction forces, the construction of a classic seal and a seal with reduced resistance to movement. Because the lip-shaft system is a specific friction pair, the focus has been on local micro contact conditions as a parameter that determines global motion resistances on a macro scale. Since the occurrence of premature sealing failure in spite of small costs of the element itself generates serious costs of repair and downtime of the transport fleet, the problem of durability and reliability of the described type of seals remains valid.
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Ismail, Nagham, Nesreen Ghaddar, and Kamel Ghali. "Determination of segmental and overall ventilation of clothed walking human by means of electric circuit analogy." Textile Research Journal 88, no. 5 (December 22, 2016): 586–601. http://dx.doi.org/10.1177/0040517516685284.
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A new simplified model has been developed to determine the ventilation induced by swinging motion and external wind for a fabric clothed cylinder representing a limb or a trunk. The simplified model is based on an analogy between air flow and an electric circuit. When a clothed body segment is subject to external wind, the microclimate air flow electric circuit is represented by resistances. When the clothed segment is subject to a swinging motion, the air flow electric circuit is composed of inductance and resistance elements. The model is validated by comparing the predicted ventilation rates to published experimental data in different conditions: varying permeability, wind speeds, swinging frequencies (for the clothed arm), walking conditions, and aperture configurations. The predictions of the simplified model lie within the standard deviation range of the published experiments. Moreover, although it is simplified, the relative error between the simplified model and the published experiment of an oscillating limb is considered acceptable (18%).
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Volgin, George. "The hydraulic resistance coefficient in the conditions of simultaneous effect of Re, Fr and Unknown node mfrac found in MathML fragment.$ {B \over h} $." E3S Web of Conferences 97 (2019): 05031. http://dx.doi.org/10.1051/e3sconf/20199705031.
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One of the most important tasks of engineering hydraulics is to determine the energy loss during the motion of the fluid flow. The study of the question of whether the patterns of hydraulic resistances are similar in a calm and turbulent flow is relevant in the design of hydraulic structures. In most cases, a turbulent regime of fluid motion is observed in various applications, but to date, the theory of turbulence is not considered complete. When designing hydraulic structures, inaccuracies in the existing calculation methods can lead to a decrease in the efficiency and reliability of the entire spillway structure as a whole. The need for an integrated approach to the analysis of the impact on the hydraulic resistance of various factors is noted (degree of spread $ \left( {{B \over h}} \right) $), the degree of turbulence (Re) and the degree of flow roughness (Fr)), which is not always provided by known dependencies and methods of calculation. On the basis of our own experimental data, a new formula for calculating the hydraulic resistance of turbulent flows in smooth channels was obtained. The functional dependence of the hydraulic resistance coefficient on the parameters $ \left( {{B \over h}} \right) $, Re and Fr is obtained.
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Noh, Jinhong, Pilkee Kim, and Yong-Jin Yoon. "Load Resistance Optimization of a Magnetically Coupled Two-Degree-of-Freedom Bistable Energy Harvester Considering Third-Harmonic Distortion in Forced Oscillation." Sensors 21, no. 8 (April 10, 2021): 2668. http://dx.doi.org/10.3390/s21082668.
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In this study, the external load resistance of a magnetically coupled two-degree-of-freedom bistable energy harvester (2-DOF MCBEH) was optimized to maximize the harvested power output, considering the third-harmonic distortion in forced response. First, the nonlinear dynamic analysis was performed to investigate the characteristics of the large-amplitude interwell motions of the 2-DOF MCBEH. From the analysis results, it was found that the third-harmonic distortion occurs in the interwell motion of the 2-DOF MCBEH system due to the nonlinear magnetic coupling between the beams. Thus, in this study, the third-harmonic distortion was considered in the optimization process of the external load resistance of the 2-DOF MCBEH, which is different from the process of conventional impedance matching techniques suitable for linear systems. The optimal load resistances were estimated for harmonic and swept-sine excitations by using the proposed method, and all the results of the power outputs were in excellent agreements with the numerically optimized results. Furthermore, the associated power outputs were compared with the power outputs obtained by using the conventional impedance matching technique. The results of the power outputs are discussed in terms of the improvement in energy harvesting performance.
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Uralov, Bakhtiyor, Sanatjon Khidirov, Farokhiddin Uljaev, Ikboloy Raimova, Khumoyun Kholmatov, and Alisher Allanazarov. "Hydraulic resistances of derivation channels of hydropower facilities." E3S Web of Conferences 274 (2021): 03010. http://dx.doi.org/10.1051/e3sconf/202127403010.
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Currently, many authors have studied the uniform axisymmetric pressure head laminar and turbulent movement of water in hydraulic smooth and rough (with uniform roughness) pipes of circular cross-section. The results obtained in the study of a plane-parallel turbulent flow in pressure channels allow here only to outline the structure of the corresponding dependencies and to clarify the simplest case of unpressurized fluid movement, when this movement can also be reduced to plane-parallel or, in other words, to movement in channel of infinitely large width with a flat bottom. In all other cases, the only way to solve the problem is experiment. But the possibilities of the experiment are limited, as are limited, and in a number of cases debatable, and the information accumulated to date on the uniform free-flow motion of fluid in channels of various cross-sectional shapes. The unpressurized uniform movement of fluid in channels of various cross-sectional shapes has been completely insufficiently studied. The construction of numerous free-flow watercourses, as well as machine channels of pumping stations, requires scientifically based calculation methods. For the correct establishment of hydraulic calculation methods, a sufficiently deep study of the physical essence of the phenomena occurring in the free-flow derivation channels is necessary. The extensive construction of numerous free-flow watercourses, as well as hydroelectric power plant (HPP) derivation channels, requires scientifically based calculation methods. For the correct establishment of hydraulic calculation methods, a sufficiently deep study of the physical essence of the hydraulic phenomena occurring in the free-flow derivation channels of HPPs is necessary.
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Muzychka, Y. S., and M. M. Yovanovich. "Thermal Resistance Models for Non-Circular Moving Heat Sources on a Half Space." Journal of Heat Transfer 123, no. 4 (January 8, 2001): 624–32. http://dx.doi.org/10.1115/1.1370516.
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Solutions to stationary and moving heat sources on a half space are reviewed for rectangular and elliptic contacts. The effects of shape, heat flux distribution, and orientation with respect to the direction of motion are examined. The dimensionless thermal resistance is shown to be a weak function of heat source shape if the square root of contact area is used as a characteristic length scale. Simple expressions are developed for calculating total thermal resistances of non-circular moving heat sources by combining asymptotic solutions for large and small values of the Peclet number. Both uniform and parabolic heat flux distributions are examined. A model is developed for predicting average or maximum flash temperatures of real sliding contacts. Comparisons of the proposed model are made with numerical solutions for two cases involving non-circular contacts.
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Kęcik, Krzysztof. "Energy Recovery from a Non-Linear Electromagnetic System." Acta Mechanica et Automatica 12, no. 1 (March 1, 2018): 11–18. http://dx.doi.org/10.2478/ama-2018-0002.
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AbstractThe paper presents study of a pseudo-magnetic levitation system (pseudo-maglev) dedicated for energy harvesting. The idea rely on motion of a pseudo-levitating magnet in a coil’s terminal. The study based on real prototype harvester system, which in the pendulum dynamic vibration absorber is applied. For some parameters, the stability loss caused by the period doubling bifurcation is detected. The coexistence of two stable solutions, one of which is much better for energy harvesting is observed. The influence of the pseudo-maglev parameters on the recovered current and stability of the periodic solutions is presented in detail. The obtained results show, that the best energy recovery occurs for the high pseudo-maglev stiffness and close to the coil resistance. The amplitude’s excitation, the load resistances and the coupling coefficient strongly influence on the system’s response.
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Dollar, Anna, and Paul S. Steif. "Interface Blunting of Matrix Cracks in Fiber-Reinforced Ceramics." Journal of Applied Mechanics 59, no. 4 (December 1, 1992): 796–803. http://dx.doi.org/10.1115/1.2894045.
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A crack impinging upon an interface that can debond and then offer frictional resistance is studied theoretically. The central question at issue is the level of the remote load at which the crack penetrates the interface, whether or not some debonding of the interface occurs first. To answer this question, we compute the stress enhancement experienced by the impinged material—averaged over a microstructural length such as the fiber diameter—as a function of interface parameters. The solution to this elasticity problem is arrived at by means of distributed dislocations to represent relative motion at the interface. Special care needs to be taken to account properly for the contact problem at the interface. Not unexpectedly, it is found that higher debond energies and greater frictional resistances lead to higher stress concentrations and, hence, to lower remote failure loads.
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Kigami, Jun. "Effective resistances for harmonic structures on p.c.f. self-similar sets." Mathematical Proceedings of the Cambridge Philosophical Society 115, no. 2 (March 1994): 291–303. http://dx.doi.org/10.1017/s0305004100072091.
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In mathematics, analysis on fractals was originated by the works of Kusuoka [17] and Goldstein[8]. They constructed the ‘Brownian motion on the Sierpinski gasket’ as a scaling limit of random walks on the pre-gaskets. Since then, analytical structures such as diffusion processes, Laplacians and Dirichlet forms on self-similar sets have been studied from both probabilistic and analytical viewpoints by many authors, see [4], [20], [10], [22] and [7]. As far as finitely ramified fractals, represented by the Sierpinski gasket, are concerned, we now know how to construct analytical structures on them due to the results in [20], [18] and [11]. In particular, for the nested fractals introduced by Lindstrøm [20], one can study detailed features of analytical structures such as the spectral dimensions and various exponents of heat kernels by virtue of the strong symmetry of nested fractals, cf. [6] and [15]. Furthermore in [11], Kigami proposed a notion of post critically finite (p.c.f. for short) self-similar sets, which was a pure topological description of finitely ramified self-similar sets. Also it was shown that we can construct Dirichlet forms and Laplacians on a p.c.f. self-similar set if there exists a difference operator that is invariant under a kind of renormalization. This invariant difference operator was called a harmonic structure. In Section 2, we will give a review of the results in [11].
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Reddy, A. Somi, K. S. S. Murthy, and S. K. Biswas. "Wear and Seizure of Aluminium-Silicon Piston Alloys in Reciprocating Motion against Steel." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 209, no. 4 (December 1995): 287–96. http://dx.doi.org/10.1243/pime_proc_1995_209_439_02.
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Aluminium-silicon alloy pins were dry slid in unidirectional and reciprocating sliding against steel counterfaces in a normal pressure range of 0.39–26 M Pa and a sliding speed range of 0.6–1.8 m/s. Changing the mode of sliding from unidirectional to reciprocating as well as an increase in reciprocating speed were found to affect wear and seizure resistances adversely. Alloying additions of copper and magnesium to the base metal, on the other hand, were found to improve both of these properties. The temperature rise of the pin during sliding and the mechanical behaviour of the test alloys in compression in a temperature range of 25 300 °C and a strain rate range of 0.1–100/s were recorded and the data incorporated into a qualitative model to account for the wear and seizure behaviour of the test materials.
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Ohadi, A. R., and G. Maghsoodi. "Simulation of Engine Vibration on Nonlinear Hydraulic Engine Mounts." Journal of Vibration and Acoustics 129, no. 4 (April 9, 2007): 417–24. http://dx.doi.org/10.1115/1.2748459.
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In this paper, vibration behavior of engine on the nonlinear hydraulic engine mount, including inertia track and decoupler, is studied. In this regard, after introducing the nonlinear factors of this mount (i.e., inertia and decoupler resistances in turbulent region), the vibration governing equations of engine on one hydraulic engine mount are solved and the effect of nonlinearity is investigated. In order to have a comparison between the rubber and the hydraulic engine mounts, a six-degree-of-freedom four-cylinder V-shaped engine under shaking and balancing mass forces and torques is considered. By solving the time domain nonlinear equations of motion of the engine on three inclined mounts, translational and rotational motions of an engine body are obtained for different engine speeds. Transmitted base forces are also determined for both types of engine mount. Comparison of rubber and hydraulic mounts indicates the efficiency of a hydraulic one in the low-frequency region.
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Arsene, Sorin. "Influence of Wind on the Aerodynamic Resistance for a Case of the Arrangement of the Equipment on Locomotive Bodywork LE 060EA." Applied Mechanics and Materials 809-810 (November 2015): 1151–56. http://dx.doi.org/10.4028/www.scientific.net/amm.809-810.1151.
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In the case of electric railway vehicles of surface, the equipments which allow power supply are placed on their bodywork. The mode to dispose these equipments contributes to increase the resistance to motion of the vehicle due to the variation cross-section area. Gusts of wind that occurs during the movement of vehicles lead to increased aerodynamic forces. As a model analyzed, we considered the situation determined by the dispose of the equipments supply on the body of electric locomotive type LE 060 EA of 5100 kW, when such a vehicle is travelling with the first post station in the driving direction. The equipment’s components of supply were modeled geometric at scale 1: 1 in 3D. The obtained assembly was imported in an air flow simulation program to determine the aerodynamic resistances. To observe which is the influence of the gusts wind regarding the resistance to moving we considered five point values for wind speed: 5m / s, 10m / s, 15m / s, 20m / s and 25m / s. With results of the simulations we performed a comparative analysis.
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Kuhlmann-Wilsdorf, D., Y. J. Chang, L. B. Johnson, and L. J. Bredell. "Friction, Wear, and Interfacial Electrical Resistance. Part I: The Hoop Apparatus." Journal of Tribology 109, no. 4 (October 1, 1987): 604–8. http://dx.doi.org/10.1115/1.3261516.
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An apparatus has been developed for the gathering of data from which, through suitable analysis, detailed information on the momentary condition of a sliding interface may be obtained. The information includes the number of the contact spots, the electrical resistivity of the interfacial film, and the flash temperature at the contact spots. The apparatus provides for the continuous simultaneous recording of the coefficient of friction and of the interfacial electrical resistance of a slider in stick-slip motion at constant load and controllable average speed, and/or of the interfacial resistance of a slider at constant speed under controllable load. Loads between 0.3 and 10N and speeds up to 0.15m/s may be selected, in a variety of atmospheres and ambient pressures, as the apparatus is enclosed in a bell jar. It consists of a rotating cylindrical metal hoop inside of which a metal slider moves under the forces of friction and gravity, giving stick-slip behavior full play, and a slider in fixed position subjected to controllable, hydrostatically applied loads. The entire apparatus can be used with a controlled atmosphere or vacuum. The motion of the stick-slip slider, from which the coefficient of friction is inferred, is recorded on one pen of a three-pen strip-chart recorder and the electrical contact resistances between the two sliders and the hoop on the other two pens. The dependence of contact resistance on load, obtainable from the fixed slider without removing the bell jar, permits a determination of the number of contact spots provided the constriction resistance is not negligibly small compared to the film resistance. Deliberate changes of the contact spot temperature can be made by adjusting the current through the slider/hoop interfaces.
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Gallena, Sally K., Nancy Pearl Solomon, Arthur T. Johnson, Jafar Vossoughi, and Wei Tian. "Test–Retest Reliability of Respiratory Resistance Measured With the Airflow Perturbation Device." Journal of Speech, Language, and Hearing Research 57, no. 4 (August 2014): 1323–29. http://dx.doi.org/10.1044/2014_jslhr-s-13-0246.
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Purpose In this study, the authors aimed to determine reliability of the airflow perturbation device (APD) to measure respiratory resistance within and across sessions during resting tidal (RTB) and postexercise breathing in healthy athletes, and during RTB across trials within a session in athletes with paradoxical vocal fold motion (PVFM) disorder. Method Prospective, repeated-measures design. The APD measured respiratory resistance during 3 baseline assessments in 24 teenage female athletes, 12 with and 12 without PVFM. Control athletes provided data at rest and following a customized exercise challenge during each of 3 sessions. Intraclass correlation coefficient (ICC) analysis assessed strength of relationships, and repeated-measures analysis of variance assessed differences across trials and sessions. Results ICC analyses confirmed strong correlations across RTB trials for inspiratory, expiratory, and mean respiratory resistance in both groups. Inspiratory resistance decreased ~5% between sessions for control participants; expiratory and mean respiratory resistances were stable. Data from control athletes across sessions and following rigorous exercise were strongly correlated when taken at comparable intervals. Conclusions APD-measured respiratory resistance, including separate assessments for the inspiratory and expiratory phases, has strong test–retest reliability during RTB and after exercising. This suggests that the APD is a useful measurement tool for the assessment of airway function in patients suspected of having PVFM.
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Liu, Huicong, Jiankang Zhang, Qiongfeng Shi, Tianyiyi He, Tao Chen, Lining Sun, Jan Dziuban, and Chengkuo Lee. "Development of a Thermoelectric and Electromagnetic Hybrid Energy Harvester from Water Flow in an Irrigation System." Micromachines 9, no. 8 (August 9, 2018): 395. http://dx.doi.org/10.3390/mi9080395.
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A hybrid energy harvester is presented in this paper to harvest energy from water flow motion and temperature difference in an irrigating pipe at the same time. The harvester is based on the integration of thermoelectric and electromagnetic mechanisms. To harvest the water flow motion, a turbine fan with magnets that are attached on the blades is placed inside of the water pipe. Multiple coils turn the water flow energy into electricity with the rotation of the turbine. The thermoelectric generators (TEGs) are attached around the pipe, so as to harvest energy due to temperature difference. For a maximum temperature difference of 55 °C (hot side 80 °C and room temperature 25 °C), twelve serial-connected TEGs can generate voltage up to 0.346 V. Under a load resistance of 20 Ώ, the power output of 1.264 mW can be achieved. For a maximum water flow rate of 49.9 L/min, the electromagnetic generator (EMG) can produce an open circuit voltage of 0.911 V. The EMG can be potentially used as a water flow meter due to the linear relationship between water flow rate and output voltage. Under the joint action of TEG and EMG, the maximum terminal voltage for TEG is 66 mV and for EMG is 241 mV at load resistances of 10 and 100 Ώ, respectively, resulting in a corresponding power output of 0.435 and 0.584 mW.
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Elyasi, Mehrdad, Chengkuo Lee, Cheng-Yu Hsieh, and Dim-Lee Kwong. "Multi-bit memory cell using long-range non-anchored actuation for high temperature applications." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, HITEN (January 1, 2013): 000152–59. http://dx.doi.org/10.4071/hiten-ta18.
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A novel micro-electro-mechanical (MEM) based non-volatile memory (NVM) is proposed. The storage principle is based on Lorentz's transduction, utilizing long-range motion of a non-anchored element which has current carrying sliding contact with a conductive path. Position of the moving element indicates the stored data in the multi-bit cell. Data is written in the cell with displacing the moving element by Lorentz's force, is read by utilizing differential port resistances, and is held by adhesion forces. Data writing at up to 300°C, and data retention and reading for higher temperatures are reliable.
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Arafath, P. K. Yasser. "Malabar Ulema in the Shafiite Cosmopolis." Medieval History Journal 21, no. 1 (March 12, 2018): 25–68. http://dx.doi.org/10.1177/0971945817750506.
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This article is an attempt to investigate the connections between Muslim ulema of Malabar and the general Muslim population in the Indian Ocean region. The ulema were part of an ever-evolving transnational knowledge network of this region in which various kinds of scholars and texts were in continuous motion. In the sixteenth century, in the wake of the expansion of Portuguese imperial ambitions, the ulema conceived of the importance of building Islamic communities of multiple resistances around shafiite texts and discourses. It looks at the complex scribal and hortatory engagements of the Malabar ulema and examines three major forms of resistance—pietistic, jurisprudential and physical—that they produced in the larger Indian Ocean region. Therefore, this article moves beyond the existing historiography that focuses on jihad (armed resistance) narratives, and demonstrates alternative ways of reading the period—which included the multiple ways in which the ulema constructed a consistent consciousness of resistance against the Portuguese. Arguments in the article are located within the concepts of fasad (social and political disorder) and fitna (collapse of internal cohesion)—two major Islamic social and political categories. They, I show, attained very specific scribal and theological significance in the Indian Ocean textual network in the sixteenth century, and also acquired particular kinds of textual idioms.
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Falnes, J. "Wave-Energy Conversion Through Relative Motion Between Two Single-Mode Oscillating Bodies." Journal of Offshore Mechanics and Arctic Engineering 121, no. 1 (February 1, 1999): 32–38. http://dx.doi.org/10.1115/1.2829552.
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Wave-energy converters (WECs) need a reaction source against which the wave forces can react. As with shore-based WECs, sometimes also floating WECs react against a fixed point on the seabed. Alternatively, for a floating WEC, force reaction may be obtained by utilizing the relative motion between two bodies. A load force for energy conversion is assumed to be applied only to this relative motion. It is assumed that either body oscillates in one mode only (mostly, the heave mode is considered here). The system, if assumed to be linear, is proved to be phenomenologically equivalent to a one-mode, one-body system, for which the wave excitation force equals the force which is necessary to apply between the two bodies in order to ensure that they are oscillating with zero relative motion. It is discussed how this equivalent excitation force and also the intrinsic mechanical impedance of the equivalent system depend on the mechanical impedances for the two separate bodies, including the radiation impedance matrix (which combines radiation resistances and added masses). The equivalent system is applied for discussing optimum performance for maximizing the absorbed wave energy. It is shown that, for an axisymmetric system utilizing heave modes, it is possible to absorb an energy amounting to the incident wave power on a crest length which equals the wavelength divided by 2π, even though the power take-off is applied to the relative motion only. Moreover, it is shown that it is possible to obtain an equivalent excitation force which exceeds the wave excitation force on either body.
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PARCZEWSKI, Krzysztof, Kazimierz ROMANISZYN, and Henryk WNĘK. "A dynamic test of a vehicle in motion and exhaust gas emissions during alternative fuelling with gasoline and compressed natural gas (CNG)." Combustion Engines 134, no. 3 (July 1, 2008): 52–60. http://dx.doi.org/10.19206/ce-117239.
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The majority of published data on exhaust gas emissions is cited based on the test results from the NEDC driving cycle. This paper specifies the methodology of how to develop dynamic characteristics of the emissions, based on the aggregated data from the measurement of modal emissions obtained in the course of NEDC and FTP-75 driving cycles for gasoline and CNG fuelling. The presented characteristics concern a real passenger car which was tested, then the characteristics were used to calculate the exhaust gas emissions during a specially developed driving test comprising four main motion resistances and engine braking. The effect of fuel type on selected emissions of exhaust gas components has also been compared and assessed.
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Sun, Feng, Ji Ming Kong, Qiang Cai, Fa You A, and Yun Cui. "The Dynamic Responses of Anti-Slide Piles Reinforced in the Rubble Soil Landslide." Applied Mechanics and Materials 99-100 (September 2011): 379–82. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.379.
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Acoording to the servic eability limit state, use the numerical analysis the method, using the fiinte element analysis software to the elastoplastic and the big distortion on the power solidifies in the finite element model, by using above coupled non-linear numerical approach, the dynamic response of piles and the earthquake resistance reinforcement. A computation method of raft foundation is brought foward in which many factors are considered. The method corresponds to real foundation working conditions. The results indicated as follows: Under the earthquake load function, the slope and anti-slide piles displacement response was amplified as the seismic motion propagated upwards through the slope. The greater the earthquake acceleration, the larger the deformation of the anti-slide pile. And the displacements of the pile were decreased from top to bottom. The different elevational point of the dynamic moment in the change tendency is the same. the dynamic moment to increase along with the input earthquake wave acceleration increases. There were larger differences occurring in the maximum value of resistances on the partial pile lain in stable rockmass and resistance distribution forms with different accelerations in different times. The calculation indicates that the new method may better reflect the actual locating state and sliding process of debris landslide and anti-slide piles under earthquake.
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Iqbal, Muhammad, Malik Muhammad Nauman, Farid Ullah Khan, Pg Emeroylariffion Abas, Quentin Cheok, Asif Iqbal, and Brahim Aissa. "Multimodal Hybrid Piezoelectric-Electromagnetic Insole Energy Harvester Using PVDF Generators." Electronics 9, no. 4 (April 11, 2020): 635. http://dx.doi.org/10.3390/electronics9040635.
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Harvesting biomechanical energy is a viable solution to sustainably powering wearable electronics for continuous health monitoring, remote sensing, and motion tracking. A hybrid insole energy harvester (HIEH), capable of harvesting energy from low-frequency walking step motion, to supply power to wearable sensors, has been reported in this paper. The multimodal and multi-degrees-of-freedom low frequency walking energy harvester has a lightweight of 33.2 g and occupies a small volume of 44.1 cm3. Experimentally, the HIEH exhibits six resonant frequencies, corresponding to the resonances of the intermediate square spiral planar spring at 9.7, 41 Hz, 50 Hz, and 55 Hz, the Polyvinylidene fluoride (PVDF) beam-I at 16.5 Hz and PVDF beam-II at 25 Hz. The upper and lower electromagnetic (EM) generators are capable of delivering peak powers of 58 µW and 51 µW under 0.6 g, by EM induction at 9.7 Hz, across optimum load resistances of 13.5 Ω and 16.5 Ω, respectively. Moreover, PVDF-I and PVDF-II generate root mean square (RMS) voltages of 3.34 V and 3.83 V across 9 MΩ load resistance, under 0.6 g base acceleration. As compared to individual harvesting units, the hybrid harvester performed much better, generated about 7 V open-circuit voltage and charged a 100 µF capacitor up to 2.9 V using a hand movement for about eight minutes, which is 30% more voltage than the standalone piezoelectric unit in the same amount of time. The designed HIEH can be a potential mobile source to sustainably power wearable electronics and wireless body sensors.
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Khodjiev, Muksin, Ilkhom Abbazov, and Javlon Karimov. "Influence of Local Resistance on Pressure and Speed Changes in Expanded Pneumatic Conveying." E3S Web of Conferences 304 (2021): 03016. http://dx.doi.org/10.1051/e3sconf/202130403016.
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This article focuses on improving product quality and reducing costs to ensure the efficiency of the global production of cotton fiber, in recent years, an increase in the consumption of cotton fiber, its specific type and navigation, changing demand for quality indicators, production of products with certain quality indicators. In all processes of cotton production, as well as in the processes of transporting raw cotton using pneumatic transport, on the basis of analyzes, studies conducted to determine factors that have a negative impact on product quality and their elimination, to create resource-saving technologies that reduce production costs, theoretically the connection is substantiated by the pressure loss of the local resistance of the mixture of air and fibrous waste. Based on the analysis, theoretical equations of motion of a mixture of air and fibrous waste in the expanding part of the pipeline in currently used pneumatic transport systems have been developed. It has been theoretically proven that the angle of expansion of an expanding pipe depends on local resistances generated in the expanding part of the pipe during the movement of air and fibrous waste in the ginner.
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Signe Mamba, S., J. C. Magniez, F. Zoueshtiagh, and M. Baudoin. "Dynamics of a liquid plug in a capillary tube under cyclic forcing: memory effects and airway reopening." Journal of Fluid Mechanics 838 (January 12, 2018): 165–91. http://dx.doi.org/10.1017/jfm.2017.828.
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In this paper, we investigate both experimentally and theoretically the dynamics of a liquid plug driven by a cyclic periodic forcing inside a cylindrical rigid capillary tube. First, it is shown that, depending on the type of forcing (flow rate or pressure cycle), the dynamics of the liquid plug can either be stable and periodic, or conversely accelerative and eventually leading to plug rupture. In the latter case, we identify the sources of the instability as: (i) the cyclic diminution of the plug viscous resistance to motion due to the decrease in the plug length and (ii) a cyclic reduction of the plug interfacial resistance due to a lubrication effect. Since the flow is quasi-static and the forcing periodic, this cyclic evolution of the resistances relies on the existence of flow memories stored in the length of the plug and the thickness of the trailing film. Second, we show that, contrary to unidirectional pressure forcing, cyclic forcing enables breaking of large plugs in a confined space although it requires longer times. All the experimentally observed tendencies are quantitatively recovered from an analytical model. This study not only reveals the underlying physics but also opens up the prospect for the simulation of ‘breathing’ of liquid plugs in complex geometries and the determination of optimal cycles for obstructed airways reopening.
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Brodny, Jarosław. "Analysis of operation of new construction of the frictional joint with the resistance wedge / Analiza pracy nowej konstrukcji złącza ciernego z klinem oporowym." Archives of Mining Sciences 57, no. 1 (October 29, 2012): 209–27. http://dx.doi.org/10.2478/v10267-012-0015-4.
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Frictional joint is the basic part of the friction props and yielding steel frames of dog headings. It constitutes a constructional connection and have decisive influence on the basic operational parameters of the steel frames and props, i.e. their loading capacity and yielding capacity. Currently applied constructions of frictional joints characterize with low loading capacity and unstable operation. In order to improve their operational parameters a new constructional solution of frictional joint, consisting on the application of resistance wedge assembled between the cooperating sections, was developed. Application of the resistance wedge caused an increase of resistances to motion in the frictional joint, what influenced on the increase of its loading capacity and on the increase of values of axial forces in the bolts of stirrups. In the paper results of stand tests of frictional joints with the resistance wedge, subjected to the static axial compression and impact of freely falling mass, were presented. In order to determine the influence of the resistance wedge on the operational parameters of the frictional joint, obtained results were compared with the results of studies of the frictional joints without the resistance wedge. On the basis of stand tests a physical and mathematical models of the frictional joint with the resistance wedge, were developed, and utilized to simulation analysis of its operation at impulse loading. On the basis of conducted tests and analysis one can state, that application of the resistance wedge influences on the enhancement of loading capacity, improves the state of loading the bolts in stirrups, and creates possibility of regulation of operational characteristics of the frictional joints
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Tobin, M. J., W. Perez, S. M. Guenther, R. F. Lodato, and D. R. Dantzker. "Does rib cage-abdominal paradox signify respiratory muscle fatigue?" Journal of Applied Physiology 63, no. 2 (August 1, 1987): 851–60. http://dx.doi.org/10.1152/jappl.1987.63.2.851.
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Studies suggesting that abnormal motion of the rib cage (RC) and abdomen (Ab) may indicate respiratory muscle fatigue have not separated the influence of respiratory load from that of fatigue in its pathogenesis. We hypothesized that abnormalities on RC-Ab motion are primarily related to increased load rather than fatigue. We tested this hypothesis in subjects breathing against resistive loads while maintaining 30 and 60% of maximum mouth pressure (Pmmax). RC-Ab asynchrony and paradox and the degree of variation in compartmental contribution to tidal volume were measured by inductive plethysmography and quantitated by the Konno-Mead method of analysis. Comparing measurements of base line and 30 and 60% of Pmmax indicated that the degree of asynchrony, paradox, and variation in compartmental contribution were significantly related to the level of the load; significant abnormalities were observed at even 30% of Pmmax, a target pressure that can be sustained indefinitely. In another group of subjects, fatigue was induced by sustaining 60% of Pmmax to the limits of tolerance. Indexes of abnormal RC-Ab motion increased from base line during the 1st min of loaded breathing but displayed no progression from the beginning to the end of the fatigue run. Immediately on discontinuation of the load, the indexes returned to levels similar to base line despite persistence of the fatigue state. These results in healthy subjects breathing against severe resistances indicate that RC-Ab asynchrony and paradox and variation in compartmental contribution to tidal volume are predominantly due to increases in respiratory load rather than muscle fatigue.
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Bellmann, Malte, Thomas Maximilian Köhler, and Thomas Schmalz. "Comparative biomechanical evaluation of two technologically different microprocessor-controlled prosthetic knee joints in safety-relevant daily-life situations." Biomedical Engineering / Biomedizinische Technik 64, no. 4 (August 27, 2019): 407–20. http://dx.doi.org/10.1515/bmt-2018-0026.
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Abstract Safety-relevant gait situations (walking on stairs and slopes, walking backwards, walking with small steps, simulated perturbations of swing phase extension) were investigated in a motion analysis laboratory with six unilateral transfemoral amputees using two different microprocessor-controlled prosthetic knee joints (Rheo Knee XC, C-Leg). A randomized crossover design was chosen. The study results imply that the performance and safety potential of a microprocessor-controlled knee joint can be associated with the individual control algorithms and the technological concepts that are implemented to generate motion resistances for controlling flexion and extension movements. When walking with small steps, advantages of the “default swing” concept used in the Rheo Knee XC were identified due to a highly reproducible swing phase release. However, when walking backwards, this concept may lead to an uncontrolled knee flexion which partly resulted in falls. When walking down stairs, walking on slopes or while recovering from a stumble after perturbations of the swing phase extension, the C-Leg demonstrated a reliable prosthetic side load-bearing capacity resulting in reduced loading on the residual body. In contrast, the Rheo Knee XC required increased compensatory movements of the remaining locomotor system in order to compensate for reduced load-bearing and safety reserves.
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Brusasco, V., D. O. Warner, K. C. Beck, J. R. Rodarte, and K. Rehder. "Partitioning of pulmonary resistance in dogs: effect of tidal volume and frequency." Journal of Applied Physiology 66, no. 3 (March 1, 1989): 1190–96. http://dx.doi.org/10.1152/jappl.1989.66.3.1190.
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To determine the sensitivity of pulmonary resistance (RL) to changes in breathing frequency and tidal volume, we measured RL in intact anesthetized dogs over a range of breathing frequencies and tidal volumes centering around those encountered during quiet breathing. To investigate mechanisms responsible for changes in RL, the relative contribution of airway resistance (Raw) and tissue resistance (Rti) to RL at similar breathing frequencies and tidal volumes was studied in six excised, exsanguinated canine left lungs. Lung volume was sinusoidally varied, with tidal volumes of 10, 20, and 40% of vital capacity. Pressures were measured at three alveolar sites (PA) with alveolar capsules and at the airway opening (Pao). Measurements were made during oscillation at five frequencies between 5 and 45 min-1 at each tidal volume. Resistances were calculated by assuming a linear equation of motion and submitting lung volume, flow, Pao, and PA to a multiple linear regression. RL decreased with increasing frequency and decreased with increasing tidal volume in both isolated and intact lungs. In isolated lungs, Rti decreased with increasing frequency but was independent of tidal volume. Raw was independent of frequency but decreased with tidal volume. The contribution of Rti to RL ranged from 93 +/- 4% (SD) with low frequency and large tidal volume to 41 +/- 24% at high frequency and small tidal volume. We conclude that the RL is highly dependent on breathing frequency and less dependent on tidal volume during conditions similar to quiet breathing and that these findings are explained by changes in the relative contributions of Raw and Rti to RL.
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Nagase, T., A. Moretto, and M. S. Ludwig. "Airway and tissue behavior during induced constriction in rats: intravenous vs. aerosol administration." Journal of Applied Physiology 76, no. 2 (February 1, 1994): 830–38. http://dx.doi.org/10.1152/jappl.1994.76.2.830.
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The distribution of contractile agonist during intravenous (i.v.) or aerosol (AR) administration is likely to be different. We questioned whether the different pattern of distribution would result in different effects on lung tissue response. We measured tracheal and alveolar pressure in open-chest mechanically ventilated [frequency 1 Hz, tidal volume 8 ml/kg, positive end-expiratory pressure (PEEP) 3 cmH2O] rats under control conditions and after i.v. or AR administration of saline or methacholine (MCh; i.v., 50 micrograms.kg-1.min-1; AR, 256 mg/ml). We calculated lung elastance and resistances of lung, tissue, and airway by fitting the equation of motion to changes in tracheal and alveolar pressure. Lungs were then frozen in situ with liquid nitrogen (PEEP=3 cmH2O) and processed via freeze substitution. Airway constriction was assessed by measuring the ratio of airway lumen to ideally relaxed area. Tissue distortion was assessed by measuring mean linear intercept between alveolar walls (Lm), atelectasis index (ATI) derived by calculating ratio of tissue to air space, and SD of Lm and ATI. I.v. and AR MCh increased lung resistance to a similar degree. However, changes in tissue resistance and lung elastance after AR MCh were significantly greater than those after i.v. MCh, whereas the change in airway resistance was significantly less. After i.v. MCh, airway constriction was prominent and evenly distributed. After AR MCh, airway constriction was less prominent and decreased as airway size decreased. Tissue distortion, i.e., SD of Lm and ATI, was significantly greater after AR than i.v. MCh.(ABSTRACT TRUNCATED AT 250 WORDS)
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ROMANISZYN, Kazimierz. "Conception of gear ratios selection between the engine and the electric machine in the hybrid drive systems." Combustion Engines 160, no. 1 (February 1, 2015): 56–61. http://dx.doi.org/10.19206/ce-116902.
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Modern vehicles with hybrid combustion-electric drive systems are an important element in the strategy for reducing fuel consumption and emissions of exhaust gas components. Determinant of the use and development is to achieve substantial benefits in terms of classical powertrain vehicles equipped with internal combustion engines. This paper presents the concept of kinematic ratio selection between the engine and the electric machine. This concept is based on the analysis of the internal combustion engine load caused by the resistances of motion and the best possible assessment of the additional load caused by the operation of the generator. It is proposed that the energy transferred to the generator was taken in a most preferred area of the engine performance characteristics and generator by changing kinematic ratio between the engine and the generator. The described concept can also be used for the recovery of vehicles braking energy.
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Choi, JinWook, Soram Oh, Yu-Chan Kim, Kwang-Koo Jee, KeeYeon Kum, and SeokWoo Chang. "Fracture Resistance of K3 Nickel-Titanium Files Made from Different Thermal Treatments." Bioinorganic Chemistry and Applications 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/6374721.
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The purpose of this study was to compare fracture resistances of K3 nickel-titanium files made from different thermal treatments. K3 (SybronEndo, Orange, CA), K3XF (SybronEndo), and experimentally heat treated K3 (K3H) were used. For the cyclic fatigue test, the samples were rotated with up-and-down motion in the artificial canal with the curvature of 60 degrees until the fracture occurred. The number of cycles to fracture (NCF) was measured. For the torsional fracture test, the samples were tightly bound and rotated until the fracture occurred. Elastic modulus (EM), ultimate torsional strength (UTS), and angle of rotation to fracture (ARF) were measured. The results were statistically analyzed by one-way ANOVA. The NCF of K3H was higher than those of K3 and K3XF (P<0.05). The EM of K3XF and K3H was lower than that of K3 (P<0.05). There was no significant difference in UTS. The ARF of K3XF was higher than that of K3 (P<0.05). K3XF and K3H showed more flexibility than K3. The maximum torsional angle of K3XF was higher than that of K3, but there was no significant difference on the UTS in all three groups.
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Łebkowski, Andrzej. "Analysis of the Use of Electric Drive Systems for Crew Transfer Vessels Servicing Offshore Wind Farms." Energies 13, no. 6 (March 20, 2020): 1466. http://dx.doi.org/10.3390/en13061466.
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The article presents issues related to the possibility of using electric propulsion systems in units used to transport crews servicing wind towers at sea. Offshore wind energy issues are discussed. Proposals for electric propulsion systems that could be used on units for transporting crews servicing offshore wind farms are presented. The possibility of using purely electrical drive systems or hybrid drive systems operating in a diesel-electric configuration is analyzed. By observing the motion of real CTV units, based on the data from the MarineTraffic service, a mathematical simulation model was developed, for which a number of simulations were carried out in the Modelica environment. The developed mathematical model takes into account the dynamic loads acting on the ship’s hull, hydrodynamic resistances, electric and diesel propulsion systems’ properties together with their individual elements’ characteristics. The tests of the electric propulsion system showed reduced fuel consumption (approx. 60%) and harmful gas emissions to the atmosphere (approximately 70%) in relation to conventional, internal combustion engine propulsion.
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Azhari, Budi, and Fransisco Danang Wijaya. "Quasi-flat linear PM generator optimization using simulated annealing algorithm for WEC in Indonesia." Journal of Mechatronics, Electrical Power, and Vehicular Technology 10, no. 1 (December 17, 2019): 29. http://dx.doi.org/10.14203/j.mev.2019.v10.29-35.
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Linear permanent magnet generator (LPMG) is an essential component in recent wave energy converter (WEC) which exploits wave’s heave motion. It could be classified into tubular-type, flat-tricore type, and quasi-flat type. In previous researches, these three models have been studied and designed for pico-scale WEC. Design optimization has further been conducted for flat-tricore LPMG, by using simulated annealing (SA) algorithm. It modified some parameters to minimize the resulted copper loss. This paper aims to optimize a quasi-flat LPMG design by applying SA algorithm. The algorithm would readjust the initial LPMG parts dimension. Then, the output of the optimized design would be analyzed and compared. The results showed that the optimization could reduce the copper loss by up to 73.64 % and increase the efficiency from 83.2 % to 95.57 %. For various load resistances, the optimized design also produces larger efficiency. However, the optimized design has a larger size and produces larger cogging force than the initial design.
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Zhang, J., and Y. Shao. "A new parameterization of particle dry deposition over rough surfaces." Atmospheric Chemistry and Physics 14, no. 22 (November 27, 2014): 12429–40. http://dx.doi.org/10.5194/acp-14-12429-2014.
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Abstract. In existing particle dry deposition schemes, the effects of gravity and surface roughness elements on particle motion are often poorly represented. In this study, we propose a new scheme to overcome such deficiencies. Particle deposition velocity is a function of aerodynamic, surface-collection and gravitational resistances. In this study, the effect of gravitation settling is treated analytically. More importantly, the new scheme takes into consideration the impacts of roughness elements on turbulent particle diffusion and surface particle collection. A relationship between aerodynamic and surface-collection processes is established by using an analogy between drag partition and deposition-flux partition. The scheme is then tested against a wind-tunnel data set for four different surfaces and a good agreement between the scheme predictions and the observations is found. The sensitivity of the scheme to the input parameters is tested. Important factors which affect particle deposition in different particle size ranges are identified. The scheme shows good capacity for modeling particle deposition over rough surfaces.