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1
Li, Han Yang, Ying Dai, and Xiao Fei Lyu. "Application of Carbon Fiber Reinforced Composites on Lightweight Design of Articulated Platform." Materials Science Forum 921 (May 2018): 85–90. http://dx.doi.org/10.4028/www.scientific.net/msf.921.85.
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For the purpose of weight saving, the heavy metal articulated platform, which is used in Bus Rapid Transit (BRT) vehicles to connect the front and rear compartments, is replaced with carbon fiber composite material. Composites articulated plates are designed based on the requirements of shape, size, positioning, connection and load of steel articulated platform. Optimization design is applied to high stress region in the articulated plates to provide references for the improvement and lightweight design of the articulated platform.
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Ayuningtyas, Purwati, Sugito Sugito, and Di Asih I. Maruddani. "PENENTUAN MODEL ANTREAN NON-POISSON DAN PENGUKURAN KINERJA PELAYANAN BUS RAPID TRANSIT TRANS SEMARANG (STUDI KASUS: SHELTER PEMBERANGKATAN BRT KORIDOR V)." Jurnal Gaussian 10, no. 1 (February 28, 2021): 1–10. http://dx.doi.org/10.14710/j.gauss.v10i1.30932.
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One of the queue systems that is often found in daily life is the transportation service system, for example a queue system at the shelters departure of corridor V Bus Rapid Transit (BRT) Trans Semarang. Corridor V has three departure shelters, they are Shelter Victoria Residence, Shelter Marina, and Shelter Bandara Ahmad Yani. Corridor V was choosen, because of its high load factor on January to June 2019. Based on the observation, the service time at the departure shelter is usually longer than the normal shelter. This causes the rise of queue at the departure shelters. The queue at the departure shelters can hamper the arrival of BRT at the other shelters, so the application of the queue theory is needed to find out the extent of operational effectiveness at the departure shelters. The resulting queue model is the Non-Poisson queue model, the queue model for Victoria Residence Shelter: (DAGUM/GEV/1):(GD/∞/∞), Marina Shelter: (DAGUM/G/1):(GD/∞/∞), and Bandara Ahmad Yani Shelter: (GEV/GEV/1):(GD/∞/∞). Based on the value from measurement of the queue system performance, it can be conclude that the three departure shelters of corridor V BRT Trans Semarang have some optimal condition. Keywords: Shelter Departure of Corridor V, Non-Poisson Queueing Model, Dagum, Generalized Extreme Value, System Perfomance Measure
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Franco Lima, Lucas, Rodrigo Castelan Carlson, Werner Kraus Junior, Lucas Zimmermann, and Luiz Alberto Koehler. "Load-sensitive bus headway control for reducing onboard passenger waiting time." TRANSPORTES 29, no. 3 (December 31, 2021): 2650. http://dx.doi.org/10.14295/transportes.v29i3.2650.
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Regularity in the bus schedule on low frequency lines or the maintenance of headways on high frequency lines are desired in the operation of public transportation. Bus holding is a technique used for this purpose, but it may incur in delays for onboard passengers. Previous work based on a predictive control method identified a better performance when the holding actions were concentrated in stations where the buses were emptier. Based on these results, the forward headway and the two-way headway feedback control methods, both operated with static gains and mathematically and computationally simpler than predictive control, are modified to operate with variable gains according to the bus load using two different techniques. A variable slack, dependent on the bus load, is also incorporated into the controllers. Microsimulations of a BRT corridor with concentrated and distributed demand patterns have shown that the proposed techniques improve the system performance when compared to the corresponding methods with fixed gain.
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Shadnam Zarbil, Mohammad, Abolfazl Vahedi, Hossein Azizi Moghaddam, and Pavel Aleksandrovich Khlyupin. "Design and Sizing of Electric Bus Flash Charger Based on a Flywheel Energy Storage System: A Case Study." Energies 15, no. 21 (October 28, 2022): 8032. http://dx.doi.org/10.3390/en15218032.
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At present, the trend of all sectors and industries, especially the oil and gas industry, is towards reducing carbon dioxide emissions. Along with the modernization of technological processes, special attention has been paid to the reduction in greenhouse gas emissions from vehicles that run on gasoline and diesel. An effective solution in this field is the transition from vehicles with combustion engines to electric vehicles, similar to the use of the electric bus in public transportation. How to charge these electric buses is a challenge for researchers. By proposing a flash charging method for electric buses, the feasibility of using these buses is obtained. Due to the pulsating nature of the power demand in this charging method, the prevention of negative effects on the network by this type of load should be considered. These negative effects can include power quality problems, voltage drop, frequency instability, and overload of transmission lines and transformers. This paper presents a flywheel energy storage system (FESS)-based flash charging station for electric buses. The specifications of the components of this charging station are designed and sized for a case study for line 1 of Tehran Bus Rapid Transit (BRT). A charging strategy based on the proposed charging cycle is presented to minimize the high-power short-duration demand from the grid. The energy consumption of the electric bus based on the electricity consumption model is calculated. Based on theoretical calculations, for the case study, there is a need for installing 12 flash charging stations based on FESS in line 1 Tehran BRT. In this line, an electric bus with a battery capacity of 80 kWh is proposed. The power and energy capacity of these charging stations are sized to 600 kW and 3.334 kWh, respectively. Additionally, an economic comparison regarding the proposed charging station is conducted. The theoretical results of the design and sizing of the proposed charging station are validated based on simulation and experimental results for a small-scale laboratory setup.
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Nowak, Andrzej S., Przemyslaw Rakoczy, and Firas I. Sheikh Ibrahim. "Proposed load combination factors for bridges with high dead-to-live load ratios." Bridge Structures 8, no. 2 (2012): 61–66. http://dx.doi.org/10.3233/brs-2012-0038.
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Berglund, Lars, Björn Aasa, Peter Michaelson, and Ulrika Aasa. "Effects of Low-Load Motor Control Exercises and a High-Load Lifting Exercise on Lumbar Multifidus Thickness." SPINE 42, no. 15 (August 2017): E876—E882. http://dx.doi.org/10.1097/brs.0000000000001989.
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Dwairi, Hazim, Omar Al-Hattamleh, and Husam Al-Qablan. "Evaluation of live-load distribution factors for high-performance prestressed concrete girder bridges." Bridge Structures 15, no. 1-2 (August 14, 2019): 15–26. http://dx.doi.org/10.3233/brs-190149.
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Huang, Kuilin, Chunxiao Zhou, Yingxin Yang, Haitao Ren, and Qingzhi Niu. "Working Load Characteristics of the PDC-Cone Composite Bit under Impact and Scraping." Shock and Vibration 2020 (January 31, 2020): 1–9. http://dx.doi.org/10.1155/2020/7540519.
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The PDC-roller hybrid bit combines the cutting structure of a tricone bit with a PDC bit. It can achieve good results, breaking rock in directional drilling, drilling in inhomogeneous formations, and drilling in formations with high levels of hardness, and it can achieve the engineering goals of increasing speed and efficiency. First, we analyzed the rock-breaking mechanism of the composite bit and the principles of cushioning, torsion reduction, and prebreaking of the cone teeth during the breaking of rock. Second, cutting load models of the cone teeth and PDC teeth were established through unit experiments and through the calculation methods of the axial force, lateral force and torque, and lateral bending moment of the composite bit. Third, the digital simulation and analysis system was improved to include the function of calculating the working load of the composite bit. Taking an 8-1/2 inch, 2 + 4 type composite bit as an example, the working load characteristics of three cutting structures (cone, blade, and composite) were analyzed and compared. The analysis shows that the composite bit has high drilling efficiency, obvious deviation advantages, and good working stability under specific formation conditions. This paper provides technical support for the performance analysis, formation adaptability evaluation, and cutting structure design optimization of the PDC-cone bit.
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Kumar Mohanta, Paritosh, Masuma Sultana Ripa, Fabian Regnet, and Ludwig Jörissen. "Effects of Supports BET Surface Areas on Membrane Electrode Assembly Performance at High Current Loads." Catalysts 11, no. 2 (February 2, 2021): 195. http://dx.doi.org/10.3390/catal11020195.
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In this work, we investigated the influence of catalyst supports, particularly Brunauer, Emmett, and Teller (BET) surface area of the catalyst support materials, on membrane electrode assembly (MEA) performance. Keeping the anode catalyst layer (CL), membrane, Pt loading, and operating condition unchanged, we prepared cathode CLs using catalysts of identical Pt content (30 wt% Pt) which were supported on carbon black materials having different BET surface areas. We observed optimum cell voltage at high current load when using cathode catalyst layers prepared from catalysts supported on carbons having medium-BET surface area. High-BET surface area supports, although beneficial at low current density as well as low-BET surface area supports, led to increased voltage losses at high current load due to mass transport limitations which can be explained by the electrochemically active surface area available and water management in the catalyst layer.
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He, Xia, Lin Zhong, Guorong Wang, Yang Liao, and Qingyou Liu. "Tribological behavior of femtosecond laser textured surfaces of 20CrNiMo/beryllium bronze tribo-pairs." Industrial Lubrication and Tribology 67, no. 6 (September 14, 2015): 630–38. http://dx.doi.org/10.1108/ilt-03-2015-0042.
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Purpose – This paper aims to carry out tribological experiments to explore the applications of femtosecond laser surface texturing technology on rock bit sliding bearing to enhance the lifetime and working performance of rock bit sliding bearing under high temperature and heavy load conditions. Design/methodology/approach – Surface textures on beryllium bronze specimen were fabricated by femtosecond laser ablation (800 nm wavelength, 40 fs pulse duration, 1 kHz pulse repetition frequency), and then the tribological behaviors of pin-on-disc configuration of rock bit bearing were performed with 20CrNiMo/beryllium bronze tribo-pairs under non-Newtonian lubrication of rock bit grease. Findings – The results showed that the surface texture on beryllium bronze specimens with specific geometrical features can be achieved by optimizing femtosecond laser processing via adjusting laser peak power and exposure time; more than 52 per cent of friction reduction was obtained from surface texture with a depth-to-diameter ratio of 0.165 and area ratio of 5 per cent at a shear rate of 1301 s−1 under the heavy load of 20 MPa and high temperature of 120°C, and the lubrication regime of rock bit bearing unit tribo-pairs was improved from boundary to mixed lubrication, which indicated that femtosecond laser ablation technique showed great potential in promoting service life and working performance of rock bit bearing. Originality/value – Femtosecond laser-irradiated surface texture has the potential possibility for application in rock bit sliding bearing to improve the lubrication performance. Because proper micro dimples showed good lubrication and wear resistance performance for unit tribo-pairs of rock bit sliding bearing under high temperature, heavy load and non-Newtonian lubrication conditions, which is very important to improve the efficiency of breaking rock and accelerate the development of deep-water oil and gas resources.
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Neal, Brent. "Photoshop and 12-bit Digital Microscope Camera Images." Microscopy Today 12, no. 2 (March 2004): 24–25. http://dx.doi.org/10.1017/s1551929500051956.
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One problem facing owners of high-end digital microscope cameras and scanners is dealing with 12-bit TIFF format images. Because of a vagueness in the TIFF specification [1], some prograins do not load 12-bit TIFF images at all, or do not handle them gracefully. Unfortunately, Adobe Photoshop is one such program.A common problem with 12-bit images that do load in Photoshop is that the image appears to be totally black once loaded. This occurs when the camera stores the most significant bits of the image in the lower 12-bits of a 16-bit data space. Photoshop, when converting to its internal 16-bit representation, does not scale these properly, resulting in a low contrast image. This can present problems with viewing the images, or performing any processing or measurement steps that you might desire.
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Sashihara, Junji, Keiko Tanaka-Taya, Shinya Tanaka, Kiyoko Amo, Hiromi Miyagawa, Gaku Hosoi, Tomokuni Taniguchi, et al. "High incidence of human herpesvirus 6 infection with a high viral load in cord blood stem cell transplant recipients." Blood 100, no. 6 (September 15, 2002): 2005–11. http://dx.doi.org/10.1182/blood.v100.6.2005.
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Abstract Human herpesvirus 6 (HHV-6) infection in recipients of cord blood stem cell transplants (CBSCTs) was estimated by semiquantitative and real-time quantitative polymerase chain reaction (PCR) and reverse-transcription PCR. Of the CBSCT recipients, 7 (70%) of 10 had active HHV-6 infection after transplantation, and all 7 were inferred from their age to have already had a primary infection. Because HHV-6 DNA is seldom detected in cord blood, these cases were considered likely to represent reactivation. In contrast, the 3 patients without HHV-6 infection were all believed to be naive regarding HHV-6 primary infection because of their age and the results of PCR assays given before the transplantation procedure. The incidence of HHV-6 infection after transplantation was significantly higher (P < .05) than after bone marrow (BM) transplantation and peripheral blood stem cell (PBSC) transplantation, when recipients without primary HHV-6 infection prior to transplantation were excluded (CBSCT, 100%; BMT/PBSCT, 56.3%). Real-time PCR revealed a higher level of viral DNA in the peripheral blood mononuclear cells from CBSCT recipients than from BMT/PBSCT recipients or patients with exanthem subitum (P < .05). HHV-6 mRNA of the U79/80gene was also detected by reverse-transcription PCR in all analyzed patients with HHV-6 infection. Its detection was correlated with the emergence of viral DNA in the plasma and symptoms such as fever and rash. Thus, HHV-6 infection was more frequent and the viral load was higher in CBSCT recipients with prior primary infection.
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Sashihara, Junji, Keiko Tanaka-Taya, Shinya Tanaka, Kiyoko Amo, Hiromi Miyagawa, Gaku Hosoi, Tomokuni Taniguchi, et al. "High incidence of human herpesvirus 6 infection with a high viral load in cord blood stem cell transplant recipients." Blood 100, no. 6 (September 15, 2002): 2005–11. http://dx.doi.org/10.1182/blood.v100.6.2005.h81802002005_2005_2011.
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Human herpesvirus 6 (HHV-6) infection in recipients of cord blood stem cell transplants (CBSCTs) was estimated by semiquantitative and real-time quantitative polymerase chain reaction (PCR) and reverse-transcription PCR. Of the CBSCT recipients, 7 (70%) of 10 had active HHV-6 infection after transplantation, and all 7 were inferred from their age to have already had a primary infection. Because HHV-6 DNA is seldom detected in cord blood, these cases were considered likely to represent reactivation. In contrast, the 3 patients without HHV-6 infection were all believed to be naive regarding HHV-6 primary infection because of their age and the results of PCR assays given before the transplantation procedure. The incidence of HHV-6 infection after transplantation was significantly higher (P < .05) than after bone marrow (BM) transplantation and peripheral blood stem cell (PBSC) transplantation, when recipients without primary HHV-6 infection prior to transplantation were excluded (CBSCT, 100%; BMT/PBSCT, 56.3%). Real-time PCR revealed a higher level of viral DNA in the peripheral blood mononuclear cells from CBSCT recipients than from BMT/PBSCT recipients or patients with exanthem subitum (P < .05). HHV-6 mRNA of the U79/80gene was also detected by reverse-transcription PCR in all analyzed patients with HHV-6 infection. Its detection was correlated with the emergence of viral DNA in the plasma and symptoms such as fever and rash. Thus, HHV-6 infection was more frequent and the viral load was higher in CBSCT recipients with prior primary infection.
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Ghasemi, Sahar, Amir Mirmiran, Yulin Xiao, and Kevin Mackie. "Accelerated testing of super lightweight UHPC waffle deck under heavy vehicle simulator." Bridge Structures 16, no. 2-3 (January 16, 2021): 61–74. http://dx.doi.org/10.3233/brs-200176.
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A super lightweight deck can enhance load rating and functionality of a bridge, especially those identified as structurally deficient. This study was aimed to develop and experimentally validate a novel bridge deck as an ultra-lightweight low-profile waffle slab of ultra-high-performance concrete (UHPC) with either carbon fiber reinforced polymer (CFRP) or high strength steel (HSS) reinforcement. The proposed system lends itself to accelerated bridge construction, rapid deck replacement in bridges with load restrictions, and bridge widening applications without the need to replace girders. Performance and failure modes of the proposed deck were initially assessed through extensive lab experiments and finite element analysis, which together confirmed that the proposed deck panel meets the AASHTO LRFD requirements. The proposed deck system is not susceptible to punching shear of its thin slab and fails in a rather ductile manner. To evaluate its long-term performance, the system was further tested under the dynamic impact of wheel load at the Accelerated Pavement Testing (APT) facility of the Florida Department of Transportation using a Heavy Vehicle Simulator (HVS).
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Natalicchio, Cortney, Hadi Al-Khateeb, Michael J. Chajes, Zheng Y. Wu, and Harry W. Shenton III. "Model calibration of a long-span concrete cable-stayed bridge based on structural health monitoring data: Influence of concrete variability." Bridge Structures 18, no. 1-2 (September 28, 2022): 45–62. http://dx.doi.org/10.3233/brs-220195.
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Structural Health Monitoring (SHM) systems, in combination with controlled load tests, can provide valuable data for calibrating high fidelity bridge models, which can then be used for evaluating the long-term performance of the bridge, improved load ratings, and permit vehicle evaluation. The objective of this research was to calibrate a 3D model of the Indian River Inlet (IRIB) cable-stayed bridge, using strains recorded by the bridge SHM system during a controlled load test. The bridge was modeled in STAAD-Pro and calibrated using a pre-commercialized software platform that uses a Generic Algorithm to minimize the error between the measured and predicted strains. The calibration parameters were the elastic modulus of groups of the main longitudinal edge girder/deck elements, which once calibrated, could be related to the measured concrete strength of the members. Four different models were investigated, using 6, 10, 14, and 18 parameter element groups of the edge girder members. Of the different models, the 14 and 18 parameter models yielded the best results. The “design” model yielded errors as high as 42% when compared to the measured strains; the error was less than 10% for the majority of measurements for the 14-parameter model. Including the effect of the traffic barriers in the model, the weighted average concrete strength of the calibrated model was within 4% of the measured weighted strength. The calibration was shown to be insensitive to measurement noise and was validated using several unique single and multi-vehicle load cases that were heavier and more offset from the centerline of the bridge. The calibration procedure was able to capture the variability in flexural stiffness of the edge girders due to the variability of the concrete, resulting in significantly better agreement between the live load measured strains and the model predicted strains.
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Drbe, Osama F. El Hadi, and M. Hesham El Naggar. "Axial monotonic and cyclic compression behaviour of hollow-bar micropiles." Canadian Geotechnical Journal 52, no. 4 (April 2015): 426–41. http://dx.doi.org/10.1139/cgj-2014-0052.
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Micropiles are used in various applications, including low-capacity micropile networks, underpinning, and seismic retrofitting of existing foundations and high-capacity foundations for new structures. Hollow-bar micropiles have an added advantage, as they provide fast installation with a high degree of ground improvement. The current Federal Highway Administration (FHWA) design guidelines designate hollow-bar micropiles as type B, even though the FHWA construction technique is different than the technique used for typical type B, which results in an overly conservative design. In addition, the current practice for construction of hollow-bar micropiles is limited to a drilling bit / hollow-bar diameter ratio of 2.5 or less. In this paper, full-scale load tests were conducted to evaluate the suitability of FHWA design guidelines to hollow-bar micropiles installed in cohesive soil and to evaluate the performance of hollow-bar micropiles constructed with a drilling bit / hollow-bar diameter ratio of 3. Eight micropiles were constructed using 76 mm (3 in.) hollow bars (76 mm outside diameter and 48 mm inside diameter) with the air–water flushing technique and advanced to a depth of 5.75 m: six micropiles were installed using a 228 mm (9 in.) drill bit and two micropiles were installed using a 178 mm (7 in.) drill bit. All micropiles were instrumented with vibrating wire strain gauges to measure the axial strain at three stations along the micropile shaft. The load tests included four axial monotonic and four cyclic axial loading tests. The results are presented and discussed in terms of load–displacement curves and load transfer mechanism. The load test results showed that the grout–ground bond strength values proposed by the FHWA (in 2005) for type B micropiles grossly underestimate the bond strength for calculating the ultimate capacity. In addition, the toe resistance can be significant for micropiles resting on sand due to the increased toe diameter. No tangent stiffness degradation was observed in the micropile capacity after applying 15 load cycles.
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Abanihi, V. K., and K. O. Ovabor. "Economic load dispatch of Nigeria integrated high voltage generation and transmission grid using BAT algorithm." Nigerian Journal of Technology 38, no. 3 (December 12, 2019): 680. http://dx.doi.org/10.4314/njt.v38i3.20.
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Pialchenkov, V. A. "METHODS OF STUDY OF THE LOAD DEGREE OF EQUIPMENT AND CONE DRILL BIT BEARINGS." Oil and Gas Studies, no. 1 (February 28, 2015): 88–95. http://dx.doi.org/10.31660/0445-0108-2015-1-88-95.
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The methods and results of analytical and experimental studies of the load distribution in the equipment elements and between the cone drill bit bearings are considered. It was defined that the results of studies are often have a contradictory character which is explained by the high complexity of processes occurred at interaction of the cone bit with the bottom-hole.
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Fatmawati, Cut, Teuku Budi Aulia, and Muttaqin Muttaqin. "PERILAKU GESER BALOK BETON BERTULANG MUTU TINGGI DENGAN VARIASI FLY ASH BATU BARA, PASIR POZZOLAN DAN BONGKAHAN CANGKANG SAWIT." Jurnal Arsip Rekayasa Sipil dan Perencanaan 3, no. 4 (December 30, 2020): 268–77. http://dx.doi.org/10.24815/jarsp.v3i4.16717.
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The utilization of high strength concrete particularly on construction is an option in structural elements. High Strength Concrete (BMT) is a compressive strength exceeding 6000 psi or 41 MPa. High quality concrete can be obtained by mixing superplasticizers (high range water reducers) and cementitious mineral additives in the form of fly ash, pozzofume (super fly ash), and microscopy (silicafume). In this study, it will used the substitution of cement material using coal fly ash, fly ash pozzolan sand and palm shell ash fly ash, fine aggregates using pozzolan sand, coarse aggregates palm shell. The aim of this study is to compare the shear behavior of normal high quality reinforced concrete beams and beams with the addition of material substitution. The high quality reinforced concrete beam specimens were designed to experience shear failure by strengthening the bending area. Reinforced concrete beam specimens of beam size 150 mm x 300 mm x 2200 mm with shear reinforcement diameter 6 mm (fy) 423.46 MPa, compressive reinforcement 16 mm (fy) 412.39 MPa and tensile reinforcement 19 mm (fy) 462, 24 MPa. The beam specimen is pure flexural tensile strength with a size of 150 mm x 150 mm x 600 mm and a cylindrical specimen with a diameter of 150 mm x 300 mm in height. The magnitude of the flexural tensile strength for BMT-N with f cc = 44.4 MPa is 4.5, and for BMT-FBPP with f cc = 51.04 MPa which is 5.35 with FAS 0.3. The results of the two beams experienced shear failure, with a comparison of laboratory and theoretical shear capacity of 2,292 BMT-N with a maximum load of 27,200 MPa, BMT-FBPP 1,720 with a maximum load of 21,410 MPa. The values of deflection and ductility tend to decrease in BMT-FBPP beams which are equal to 19.780% and 6%.
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Pexa, Brett, Eric D. Ryan, J. Troy Blackburn, Darin A. Padua, J. Craig Garrison, and Joseph B. Myers. "Influence of Baseball Training Load on Clinical Reach Tests and Grip Strength in Collegiate Baseball Players." Journal of Athletic Training 55, no. 9 (August 28, 2020): 984–93. http://dx.doi.org/10.4085/1062-6050-0456.19.
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Context A baseball-specific training load may influence strength or glenohumeral range of motion, which are related to baseball injuries. Glenohumeral reach tests and grip strength are clinical assessments of shoulder range of motion and upper extremity strength, respectively. Objective To examine changes in glenohumeral reach test performance and grip strength between dominant and nondominant limbs and high, moderate, and low baseball-specific training-load groups. Design Repeated-measures study. Setting University laboratory and satellite clinic. Patients or Other Participants Collegiate baseball athletes (n = 18, age = 20.1 ± 1.3 years, height = 185.0 ± 6.5 cm, mass = 90.9 ± 10.2 kg). Main Outcome Measure(s) Participants performed overhead reach tests (OHRTs), behind-the-back reach tests (BBRTs), and grip strength assessments using the dominant and nondominant limbs every 4 weeks for 16 weeks. Percentage change scores were calculated between testing times. After each training session, participants provided their duration of baseball activity, throw count, and body-specific and arm-specific ratings of perceived exertion. We classified them in the high, moderate, or low training-load group based on each training-load variable: body-specific acute:chronic workload ratio (ACWR), arm-specific ACWR, body-specific cumulative load, and arm-specific cumulative load. Mixed models were used to compare training-load groups and limbs. Results The arm-specific ACWR group demonstrated as main effect for OHRT (F = 7.70, P = .001), BBRT (F = 4.01, P = .029), and grip strength (F = 8.89, P < .001). For the OHRT, the moderate training-load group demonstrated a 10.8% greater increase than the high group (P = .004) and a 13.2% greater increase than the low group (P < .001). For the BBRT, the low training-load group had a 10.1% greater increase than the moderate group (P = .011). For grip strength, the low training-load group demonstrated a 12.1% greater increase than the high group (P = .006) and a 17.7% greater increase than the moderate group (P < .001). Conclusions Arm-specific ACWR was related to changes in clinical assessments of range of motion and strength. Clinicians may use arm-specific ACWR to indicate when a baseball athlete's physical health is changing.
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Thulaseedharan, Nandhu Pillay, and Matthew Thomas Yarnold. "Prioritization of Texas prestressed concrete bridges for future truck platoon loading." Bridge Structures 16, no. 4 (March 29, 2021): 155–67. http://dx.doi.org/10.3233/brs-210181.
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Autonomous truck platoons shall soon be traveling our highway system with greater frequency. The objective of the presented study is to conduct a high-level evaluation of the Texas concrete bridge inventory when subjected to potential truck platoon loading. The National Bridge Inventory (NBI) database is utilized to the greatest extent possible. In addition, a significant literature review is performed to make assumptions allowing estimated load rating calculations for the prestressed concrete bridges likely to support future platoons (nearly 3,000 bridges). The truck platoon load ratings, combined with the NBI structural evaluation condition ratings, are utilized to prioritize each bridge. As a result, bridges are identified for more detailed evaluation prior to future truck platoon implementation. Data analysis was also performed to further understand the impact of various parameters on the load rating and prioritization results. Conclusions were drawn regarding the sensitivity of the (1) original design methodology, (2) bridge span length, (3) truck type, (4) truck spacing and (5) number of trucks within a platoon. In addition, a secondary benefit of the study is a presented framework for other bridge owners to prioritize their bridges that may be subjected to truck platoon or other heavy vehicle loading.
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Adebayo, B., and W. A. Bello. "Property Analysis for Correlation of Specific Energy with Penetration Rate and Bit Wear Rate." Advanced Materials Research 367 (October 2011): 547–53. http://dx.doi.org/10.4028/www.scientific.net/amr.367.547.
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This study evaluates rock properties for correlation of specific energy with penetration rate and bit wear rate. In order to achieve these objectives five rock samples were obtained from the study area. These samples were tested in the laboratory for uniaxial compressive strength and tensile strength using 1100kN compression machine and point load tester respectively. Also, the mineral composition of the samples was determined by thin section examination. Bit deterioration was measured with digital vernier calliper at regular intervals. The specific energy was determined from field data using empirical equations. The results of the uniaxial compressive strength of the five rock samples varied from 165-320 MPa and were classified as having very high compressive strength characteristics. The point load strength index of the samples had values ranging from 5.50 – 10.67 MPa representing the tensile strength. The result of the statistical correlation matrix revealed that penetration rate and bit wear rate are dominant factors affecting the prediction of specific energy having high coefficient of correlation. The regression model had multiple coefficient of correlation of R2 = 0.893 which means that 89.3% of variation in specific energy could be attributed to variation in penetration rate and bit wear rate. Ultimately, computer programme DRILLING PROFESSIONAL 2009 was developed to compute penetration rate, wear rate and specific energy when necessary inputs are supplied. This gives quarry operators advance information on time of drilling and bit consumption.
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Nguyen, Thanh-Binh, Minh-Tuan Le, and Vu-Duc Ngo. "Signal Detection Based on Parallel Group Detection Algorithm for High-Load Massive MIMO Systems." Wireless Communications and Mobile Computing 2019 (December 12, 2019): 1–12. http://dx.doi.org/10.1155/2019/5609740.
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In this paper, a parallel group detection (PGD) algorithm is proposed in order to address the degradation in the bit error rate (BER) performance of linear detectors when they are used in high-load massive MIMO systems. The algorithm is constructed by converting the equivalent extended massive MIMO system into two subsystems, which can be simultaneously detected by the classical detection procedures. Then, using the PGD and the classical ZF as well as the QR-decomposition- (QRD-) based detectors, we proposed two new detectors, called ZF-based PGD (ZF-PGD) and QRD-based PGD (QRD-PGD). The PGD is further combined with the sorted longest basis (SLB) algorithm to make the signal recovery more accurate, thereby resulting in two new detectors, namely, the ZF-PGD-SLB and the QRD-PGD-SLB. Various complexity evaluations and simulations prove that the proposed detectors can significantly improve the BER performance compared to their classical linear and QRD counterparts with the practical complexity levels. Hence, our proposed detectors can be used as efficient means of estimating the transmitted signals in high-load massive MIMO systems.
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Goay, Amus Chee Yuen, Deepak Mishra, and Aruna Seneviratne. "BER-Aware Backscattering Design for Energy Maximization at RFID Passive Tag." Infocommunications journal 14, no. 4 (2022): 49–55. http://dx.doi.org/10.36244/icj.2022.4.7.
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AbsThe radio frequency identification (RFID) passive tag is wireless communication device with high energy sustainability, such that it uses the incident radio frequency (RF) signal to backscatter its information. This paper investigates the output load power maximization with optimal load impedances selection in the backscatter communication (BackCom) network. The considered BackCom system comprises a reader broadcasting an unmodulated carrier to the passive tag in the downlink. The tag backscatters its information signal to the reader with binary amplitude-shift keying (BASK) modulation in the uplink. We formulated an average output load power maximization problem by jointly optimizing the reflection coefficients while satisfying the minimum bit error rate (BER) requirement and tag sensitivity constraint. To simplify the problem, we transform the BER constraint to the modulation index constraint and reduce the 4 variables problem to 2 variables convex optimization problem. Using the Karush-Kuhn-Tucker (KKT) conditions, we design an algorithm to obtain the closed-form expression for the global optimal reflection coefficients that maximize the output load power. The simulation results provide insight into the impact of the information bit probability, tag sensitivity constraint, and BER on the achievable average load power. An overall gain of around 16% signifies the utility of our proposed design.
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Yang, Jun De, Yang Yan Huang, and Wei Chen. "Study on Effect of Sintering Pressure on the Properties of Diamond Bit." Advanced Materials Research 634-638 (January 2013): 2366–72. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.2366.
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High pressure is demanded in producting diamond bit by cold-pressing. Although the pressure could be reduced by hot-pressing, a certain pressure is demanded to ensure the compactness of diamond bit matrix. Four sintering parameters, sintering temperature, holding time, sintering pressure and the pressing mode, are mainly included during producting diamond bit by hot-pressing. This article mainly discusses the effect of sintering pressure on the properties of diamond bit. First, select a general formula of diamond bit, take sintering pressure as variable, other parameters remaining immovability; then load and sinter a set of samples in this parameter. Testing and analysing the samples by mechanical properties test, such as bending, tension, compression, and rigidity, and SEM fracture analysis, we obtain the optimum sintering pressure in this formula.
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Shokrzadeh, Mohamad R., and F. Nateghi-Alahi. "Evaluation of hybrid NSM-CFRP technical bars and FRP sheets for seismic rehabilitation of a concrete bridge pier." Bridge Structures 18, no. 3-4 (January 6, 2023): 75–88. http://dx.doi.org/10.3233/brs-290180.
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Seismic retrofit is a cost-effective and sustainable solution for improving bridge structures in seismic zones. Fiber Reinforced Polymer (FRP) is commonly used to replace steel components in retrofit projects due to their light weight, high strength, and high corrosion resistance. The fabrication of novel hybrid structures from FRP and concrete is the next step researchers are addressing. In this context, the present study focuses on numerical modeling of the experimentally determined response of a hybrid FRP and concrete bridge pier subjected to quasi-static tests. The results from FEM showed strong agreement with the experimental response in terms of load-displacement curve and failure mode. After validating the model, alternative designs (changing the height of the CFRP slab, changing the height and compaction of the CFRP bar, and concrete encasement with and without CFRP slab) were numerically tested to investigate the effects of each model on the load capacity. With the conventional concrete encasement, the bearing capacity of the bridge pier can be rehabilitated, but with the CFRP plate in the above system, the bearing capacity of the bridge pier is increased by more than 60%. Therefore, it can be concluded that seismic strengthening techniques with CFRP sheets and mounted NSM-CFRP bars are suitable for concrete bridge piers.
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Katuri, Rayudu, Guduri Yesuratnam, and Askani Jayalaxmi. "BAT algorithm and Ant Colony Optimization based Optimal Reactive Power Dispatch to Improve Voltage Stability." European Journal of Engineering Research and Science 2, no. 6 (June 18, 2017): 27. http://dx.doi.org/10.24018/ejers.2017.2.6.378.
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One of the important tasks of a power system engineer is to run the system in safe and reliable mode for secure operation with increase in loading. So, it is significant to perform voltage stability analysis by optimal reactive power dispatch with Artificial Intelligence (AI) techniques. This paper presents the application of Ant Colony Optimization (ACO) and BAT algorithms for Optimal Reactive Power Dispatch (ORPD) to enhance voltage stability. The proposed ACO and BAT algorithms are used to find the optimal settings of On-load Tap changing Transformers (OLTC), Generator excitation and Static Var Compensators (SVC) to minimize the sum of the squares of the voltage stability L– indices of all the load buses. By calculating system parameters like L-Index, voltage error/deviation and real power loss for the practical Equivalent of Extra High Voltage (EHV) Southern Region Indian 24 bus system, voltage profile is improved and voltage stability is enhanced. A comparative analysis is done with the conventional optimization technique like Linear Programming (LP) for the given objective function to demonstrate the effectiveness of proposed ACO and BAT algorithms.
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Katuri, Rayudu, Guduri Yesuratnam, and Askani Jayalaxmi. "BAT algorithm and Ant Colony Optimization based Optimal Reactive Power Dispatch to Improve Voltage Stability." European Journal of Engineering and Technology Research 2, no. 6 (June 18, 2017): 27–35. http://dx.doi.org/10.24018/ejeng.2017.2.6.378.
Full textAbstract:
One of the important tasks of a power system engineer is to run the system in safe and reliable mode for secure operation with increase in loading. So, it is significant to perform voltage stability analysis by optimal reactive power dispatch with Artificial Intelligence (AI) techniques. This paper presents the application of Ant Colony Optimization (ACO) and BAT algorithms for Optimal Reactive Power Dispatch (ORPD) to enhance voltage stability. The proposed ACO and BAT algorithms are used to find the optimal settings of On-load Tap changing Transformers (OLTC), Generator excitation and Static Var Compensators (SVC) to minimize the sum of the squares of the voltage stability L– indices of all the load buses. By calculating system parameters like L-Index, voltage error/deviation and real power loss for the practical Equivalent of Extra High Voltage (EHV) Southern Region Indian 24 bus system, voltage profile is improved and voltage stability is enhanced. A comparative analysis is done with the conventional optimization technique like Linear Programming (LP) for the given objective function to demonstrate the effectiveness of proposed ACO and BAT algorithms.
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Xie, Xin Yu, Kai Zhu, Jin Yao Hua, Hong Wei Ying, and Kai Fu Liu. "Behaviour and In Situ Tests of Self-Drilling Prestressed Anchors." Applied Mechanics and Materials 130-134 (October 2011): 3536–42. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3536.
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The self-drilling prestressed anchor is a type of ground anchor used to transmit the applied tensile load into soil or rock through cement grout. The paper outlines a general construction procedure using a special self-drilling bit. Based on the load-transfer mechanism, the construction procedure is presented for load-dispersed ground anchors. In-situ pullout tests were carried out for three self-drilling prestressed anchors of the load-dispersed compression type. The test results showed that the ultimate pullout capacity could reach 800 – 1,000 kN. After prestressing, the displacement of the anchor head was decreased by 50 % – 70 % for a low load level and 30 % – 40 % for a high load level, and the displacement induced by elastic deformation was much smaller than that induced by plastic deformation. These results demonstrate that this anchor type is suitable and economical for practical engineering needs.
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Alam, Mahfooz, and Mohammad Shahid. "A Load Balancing Strategy with Migration Cost for Independent Batch of Tasks (BoT) on Heterogeneous Multiprocessor Interconnection Networks." International Journal of Applied Evolutionary Computation 8, no. 3 (July 2017): 74–92. http://dx.doi.org/10.4018/ijaec.2017070104.
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In high performance computing, heterogeneous Multiprocessor Interconnection Networks (MINs) are used for processing of compute intensive applications. These applications are distributed on the heterogeneous computational processors of MINs arranged in specific geometrical shape. MINs are also used for transfer task between two processors in a heterogeneous multistage network for better load balancing. Load balancing algorithm plays a vital role in interconnection network in order to minimize the load imbalance on the processors. In this paper, a Load Balancing Strategy with Migration cost (LBSM) is proposed to execute an independent batch of tasks on various heterogeneous MINs viz. MetaCube, X-Torus and Folded Crossed Cube having the objective of minimizing the load imbalance on processors. In simulation study, LBSM is compared with its previous work DLBS and superior performance is shown with the considered parameters under study. Further, the performance analysis of LBSM has been conducted on MetaCube, X-Torus and Folded Crossed Cube and results have been reported accordingly.
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Huang, Lu Meng, Yan Ting Zhang, Lei Zhang, and Mei Ying Liu. "Simulation Study on Drawworks Heave Compensation System of Offshore Oil Drilling." Applied Mechanics and Materials 385-386 (August 2013): 951–55. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.951.
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In order to improve the efficiency of offshore oil drilling, simplify the structure of drilling rigs, a new type of heave compensaton drawworks is put forward to realize decoupling control of motion and energy saving by hydraulic energy storage. In order to study the compensation performance of drawworks, mathematical simulation model is built, heave compensation displacement controller of fuzzy-PI and bit pressure controller of BP neural network are designed based on the high inertia load and nonlinear time-varying characteristics of the system. The simulation results show that the heave compensation maintains the absolute displacement of the hook within certain premises and reduces the effects on bit pressure by platform heave movement, automatic bit feeding keeps bit pressure steady, the bit pressure is kept in the scope prescribed by work. The research result shows that the device well meets the performance requirements of offshore drilling.
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Soeb, Md Janibul Alam, Md Shahid Iqbal, Md Abu Naser Mojumder, Muhammad Rashed Al Mamun, A. S. M. Shahjalal Atik, and Md Fahad Jubayer. "Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators." European Journal of Engineering and Technology Research 6, no. 7 (December 23, 2021): 133–39. http://dx.doi.org/10.24018/ejeng.2021.6.7.2686.
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The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.
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Soeb, Md Janibul Alam, Md Shahid Iqbal, Md Abu Naser Mojumder, Muhammad Rashed Al Mamun, A. S. M. Shahjalal Atik, and Md Fahad Jubayer. "Electrical Power Generation System: Optimal Design for Medium-Load Industries with High-Rated Generators." European Journal of Engineering and Technology Research 6, no. 7 (December 23, 2021): 133–39. http://dx.doi.org/10.24018/ej-eng.2021.6.7.2686.
Full textAbstract:
The demand for electrical power is rapidly increasing due to the rise of industries in developing countries. Power generation stations are having troubles to strike a balance between demand and generation. In this situation, it is urged that appropriate remedial action be taken. Rising power demand can be met by designing an efficient electric power generation system which will also help lowering the generation cost. It is shown that while high rated electric power generators are connected in parallel the value of neutral current is rising and the cooling temperature is also increased. Here, the goal of this experimental work is to present a new model for designing an efficient power production system for average-load (ranging up to 8000 Amp, 440 V) industries to minimize the demand on centralized interconnected grid. A scheme is proposed with four generators (2500 kVA, 2000 kVA, 2000 kVA and 1250 KVA) in parallel and enough cooling arrangement is provided with minimal cost. The coolant temperature is maintained 61 °C to 61.5 °C and at that time diesel temperature is not more than 38.5 °C. The amount of neutral-current is also optimized (up to 8.5 Amp.) which was more than 12 Amp. At the morning and afternoon, the neutral current is almost constant, but it is bit fluctuating between 7.5 Amp to 8.2 Amp at mid-day. The final outcome shows, the suggested system is efficiently stable with the change of load and generates optimal electricity.
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Askari, I. Baniasad, and M. Ameri. "Optimal sizing of photovoltaic—battery power systems in a remote region in Kerman, Iran." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 223, no. 5 (May 4, 2009): 563–70. http://dx.doi.org/10.1243/09576509jpe717.
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A solar energy system is an excellent solution for electrification of remote rural areas where the grid extension is difficult and not economical. This article presents a simple optimization method for calculating the optimum configurations of photovoltaic—battery (PV—bat) systems with high reliability and minimum cost. The proposed method has been applied to design a PV—bat system to supply a typical load requirement in a remote region in Kerman, Iran. To design an optimum stand-alone PV—bat system with high reliability and low costs, the optimization procedure, which is based on the annual electrical demand and solar radiation data, consists of two parts: the model of loss of power supply probability (LPSP) and the model of the levelized cost of energy. For the different desired LPSP requirements at given demand, the optimal numbers of solar array and battery hours of storage are obtained at the minimum system cost.
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Zheng, Lei, Chen Zhang, Xianglong Dong, Shitian Zhao, Weidong Wu, Zhi Cui, and Yaoqing Ren. "Investigations on the Wear Rate of Sintering Diamond Core Bit during the Hole Drilling Process of Al2O3 Bulletproof Ceramics." Advances in Materials Science and Engineering 2018 (November 1, 2018): 1–9. http://dx.doi.org/10.1155/2018/5010167.
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Bulletproof ceramics are usually hard and brittle with high elastic modulus, high compressive strength, and low tensile strength. While machining bulletproof ceramics, severe tool wear makes it difficult to obtain desired machining quality and efficiency, especially in hole drilling. In this work, an intensive experimental study on the overall wear rate of the sintering diamond thin-wall core bit during the hole drilling of Al2O3 bulletproof ceramics (99 wt.%) has been carried out. The quality loss of the bit after each hole drilled was selected for representing the overall wear rate of the bit. Based on experimental data, the influences of the main bit performance and machining process parameters on the overall wear rate of the bit have been analyzed. According to the results discussed, under the test conditions, finer diamond grit, higher diamond concentration, lower number of water gaps, thinner wall thickness, or lower bit load all can decrease the wear rate of the bit. However, within a certain range, the spindle speed has little influence on the overall wear resistance of the bit, but when the spindle speed increases, the machining efficiency can be significantly improved. The results obtained in this work can offer a valuable reference for the use of sintering diamond thin-wall core bits in the hole drilling of bulletproof ceramics.
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Jinping, Yu, Zou Deyong, Sun Yuanxiu, and Zhang Yin. "Simulation and Experimental Study of the Rock Breaking Mechanism of Personalized Polycrystalline Diamond Compact Bits." Journal of Engineering Science and Technology Review 13, no. 5 (2020): 122–31. http://dx.doi.org/10.25103/jestr.135.16.
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Rock breaking is a complex physical process that can be influenced by various factors, such as geometrical shape and cutting angle of rock breaking tools. Experimental study of the rock breaking mechanism of personalized bits is restricted due to long cycle and high cost. This study simulated the rock breaking mechanism of polycrystalline diamond compact (PDC) bit by combining finite element method and experiment. The simulation was performed to shorten the period and reduce the cost of studying the rock breaking mechanism of PDC bits. A rock breaking finite element model for sting cutters of personalized PDC bit was established to simulate the rock breaking process. The crack propagation pattern, dynamic stress of rock breaking, and rock breaking mechanism of sting cutters of personalized PDC bit were analyzed. The correctness of the simulation results was verified through experiments. Results demonstrate that the rock breaking load increases with the crack propagation in the fracture initiation and propagation stages, with the maximum tangential force of 1062.5 N and maximum axial force of 1850.0 N. The load changes in a small range when the crack penetrates the rock, with the tangential force of 125.0–500.0 N and axial force of 375.0–875.0 N. The rock breaking mechanism of the sting cutters of bit is consistent with maximum tensile stress theory. The rock begins to break when the tensile stress of rock is 36.9 MPa. The sting cutters of personalized PDC bit have better wear resistance than the sting cutters of conventional bit. The average wear rates of personalized PDC and conventional bits are 1.74E-4 and 2.1E-4 mm/m, respectively. This study serves as reference for shortening the study period of rock breaking mechanism, efficiently designing personalized PDC bit structure, reducing bit wear, and enhancing rock breaking efficiency.
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Kakarla, Deepti. "An optimized design approach for 8-bit pipelined ADC using high gain amplifier." i-manager’s Journal on Electronics Engineering 12, no. 2 (2022): 23. http://dx.doi.org/10.26634/jele.12.2.18529.
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Demand of high-performance converters with integrated circuits with combined features and specifications of power consumption, resolution and speed have become very dominant in many emerging applications. Pipelined ADC mixed signal system consists of Sample and Hold, Flash ADC, DAC and Gain amplifier in all the stages. In the present work, a pipeline ADC architecture has 3-stages, with each stage of 3-bits with 3-bit flash ADC followed by a 3-bit binary weighted DAC at each stage. A novel approach to design a 8-bit ADC is implemented, and this design offers less number of comparators compared to flash ADC with less circuit complexity, and 8-bit ADC is designed with improvement in resolution. It is simulated first in MATLAB, but applying 1.8Volts sinusoidal and sampling time of 40 MSPS and clock frequency 10MHz the individual blocks are implemented in LT-spice 180 nm technology with bandwidth of 40 MHz. Then a high gain amplifier is implemented by using Diode connected load differential amplifier with 10mv input voltage and 18Mhz input frequency.
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Han, Xiaoming, Qiangqiang Zhang, Shifeng Wang, Jialiang Li, and Detuo Chen. "Influence of polycrystalline diamond compact bit geometric parameters on drilling performance during gas drainage borehole in soft coal seam." Advances in Mechanical Engineering 10, no. 1 (January 2018): 168781401775066. http://dx.doi.org/10.1177/1687814017750667.
Full textAbstract:
Polycrystalline diamond compact bit is the main rock-breaking tool of gas drainage borehole. In order to investigate the influence of geometric parameters of polycrystalline diamond bit on its drilling performance, the integrated force model of polycrystalline diamond bit pressed into rock was established. The stress analysis results show that the tooth rake angle, pressing depth, and horizontal tangential displacement are the main factors to influence the normal load and the axial load of polycrystalline diamond bit. There is an optimal tooth rake angle value of polycrystalline diamond bit cutter when it is used in the soft coal seam. The drilling experiment system was built to verify the drilling performance of drill bits with different geometric structure and different tooth rake angle through drilling the soft coal wall. The experiment results show that the drilling torque and feeding resistance of polycrystalline diamond bit are higher than that of the wing bit at the beginning of drilling the soft coal wall. With the increase in the drilling depth, the feeding resistance of wing bit will increase to exceed that of the polycrystalline diamond bit. So the polycrystalline diamond bits should be selected to drill the gas drainage borehole in soft coal seam. The polycrystalline diamond bit with bigger tooth rake angle cannot cut and break the coal rock effectively, which will reduce the drilling efficiency and the feeding speed. When the tooth rake angle is smaller, polycrystalline diamond bit cannot cut in coal wall effectively, which will increase the feeding resistance. So the polycrystalline diamond bit with tooth rake angle of 15°–20° is suitable for the gas drainage borehole in soft coal seam. With the increase in the rotary speed of polycrystalline diamond bit, the cutting thickness of coal rock decreases and the horizontal tangential displacement increases. When the rotary speed of polycrystalline diamond bit is 290 r/min, the mean drilling torque and mean feeding resistance of polycrystalline diamond bit reach the minimum. Therefore, in order to reach the optimum drilling performance, the working parameters of low drilling pressure and high rotary speed are usually selected during the actual gas drainage borehole in soft coal seam.
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Babatunde, Adebayo. "Development of rock bitwear models for selected rocks in Nigeria using dominant rock properties." World Journal of Engineering 12, no. 4 (August 1, 2015): 331–40. http://dx.doi.org/10.1260/1708-5284.12.4.331.
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This work deals with the development of wear rate models for some selected rocks in Nigeria. Rock samples obtained were tested for chemical composition, point load strength index, uniaxial compressive strength, and porosity in the laboratory. These properties were correlated with wear rate. The results of statistical correlation matrix revealed that silica content, point load strength index, uniaxial compressive strength, porosity, Equivalent Quartz Content (EQC), rebounds hardness value and circularity factor are dominant rock properties affecting bit wear having high coefficient of correlation. These rock properties were used for development of regression model to predict wear rate for each of the selected rocks. The regression equation for predicting bit wear rate of porphyritic hornblende-granite is WG = 0.135 – 0.001 Is50 – 0.002EQC – 0.007n, the regression model has multiple correlation coefficient of R2 = 0.992 (99.2%), which means that 99.2% of the variation in wear rate can be attributed to variation in point load strength Index (Is50), Equivalent Quartz Content (EQC) and porosity (n) of porphyritic hornblende-granite. The results of comparison between field measured wear rate and simulated wear rate followed the same trend and the coefficient of correlation between wear rate (dependent variable) and regression standard predicted value is R2 = 0.99, which suggest that the models are valid.
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Albert, E., C. Solano, E. Giménez, D. Focosi, A. Pérez, L. Macera, J. L. Piñana, J. C. H. Boluda, F. Maggi, and D. Navarro. "The kinetics of torque teno virus plasma DNA load shortly after engraftment predicts the risk of high-level CMV DNAemia in allogeneic hematopoietic stem cell transplant recipients." Bone Marrow Transplantation 53, no. 2 (October 30, 2017): 180–87. http://dx.doi.org/10.1038/bmt.2017.235.
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Tang, Liping, Wei He, and Xiaohua Zhu. "The effect of high-frequency torsional impacts on the dynamic response of a drill string in a stick state." Advances in Mechanical Engineering 11, no. 3 (March 2019): 168781401982857. http://dx.doi.org/10.1177/1687814019828579.
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Stick–slip vibration is common in the oil well drilling process and is detrimental to down-hole equipment and drilling efficiency. In recent years, a new type of drilling technology, torsional impact drilling, has been developed to mitigate the stick–slip phenomena, particularly in the drilling of deep or abrasive formations. With this drilling technique, high-frequency torsional impacts are generated and applied to the drill bit, providing the drill bit with auxiliary energy. By mitigating or suppressing the stick–slip vibration, part of the energy wasted as a result of vibration can be regained. However, the effect of these impact loads on the dynamic response of a drill string in a stick state is unknown. In order to address this issue, a continuous system model of a drill string that includes torsional impact load was constructed. In the model, a Fourier series approach was used for the impact load, and the mechanical model was resolved with the mode superposition method. Case studies were done to understand the drill string dynamics, with and without the impact. The case study results demonstrate that high-frequency torsional impacts have little influence on the dynamic response of a drill string in a stick state.
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Krishna, Banoth, Sandeep Singh Gill, and Amod Kumar. "Design of Low-Power High-Speed 8 Bit CMOS Current Steering DAC for AI Applications." International Journal of Software Science and Computational Intelligence 14, no. 1 (January 1, 2022): 1–18. http://dx.doi.org/10.4018/ijssci.304801.
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This paper describes a current steering 8-bit DAC architecture for low power and high-speed assistance in AI networks. This design is most suitable for 5G and next-generation high-speed communication systems on chip (SoCs). This DAC keeps a constant load current and leads to faster operations in wideband portable device applications. The design is based on weighted current transmission through current mirrors wherein current reduces from MSB to LSB continuously. By choosing a low current for LSB, the power dissipation reduces. Power and area are also reduced by using a 2-bit binary to thermometer decoder. The DAC's integral nonlinearity (INL) and differential nonlinearity (DNL) are found to be within 0.4 and 0.9 LSB, respectively. The DAC's highest operating speed is 1GHz, with a power dissipation of around 24.2 mW with the supply voltage of 1.8v using 180nm CMOS technology.
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Marinello, M. M., and E. Bernard. "Wing morphology of Neotropical bats: a quantitative and qualitative analysis with implications for habitat use." Canadian Journal of Zoology 92, no. 2 (February 2014): 141–47. http://dx.doi.org/10.1139/cjz-2013-0127.
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Wing morphology has a direct influence on the flight manoeuvrability, agility, and speed of bats. Studies addressing the relationship between bat wing morphology and ecology are biased towards Old World species and few of them have addressed the ecologically rich Amazonian bat fauna. We quantitatively and qualitatively characterized the wing shape of 51 bat species found in the Brazilian Amazonia by measuring their aspect ratio (AR) and relative wing load (RWL). We found a high variability in wing shape: AR varied from 5.0862 (pygmy round-eared bat, Lophostoma brasiliense (Peters, 1866)) to 8.2774 (brown dog-faced bat, Molossus (Cynomops) paranus (Thomas, 1901)), while RWL varied from 20.0459 (spectral bat, Vampyrum spectrum (L., 1758)) to 55.3931 (Pallas’s mastiff, Molossus molossus (Pallas, 1766)). Insectivores had the largest variability, whereas frugivores and nectarivores had intermediate values with lower variability, indicating a higher flexibility in the use of space and resources. Our predictions on flight patterns are supported by capture and behavioural data from the literature, both of which point to the use of wing shape as a good proxy for habitat use and food partitioning among species. Our data are useful for integrative studies in ecology, physiology, behaviour, and evolution, and can contribute to a better understanding of the ecological interactions of Neotropical bat species.
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Vardhan, Alok. "Energy saving analysis of the hydrostatic drives used in the rotary head system of the blast hole drill rig." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 5 (March 13, 2019): 1086–97. http://dx.doi.org/10.1177/0954408919836375.
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Blast hole drill rigs are used for drilling the soft and the medium-hard rocks in open-pit mines. In such rigs, the drill bit is rotated by a hydrostatic drive. In this respect, two different type hydrostatic drives have been considered. In the first drive, the rotation of the drill bit takes place by a variable displacement pump and two low-torque high-speed hydro-motors along with a step-down gear unit (i.e. LTHS drive), whereas in the second drive an identical pump and a high-torque low-speed hydro-motor (i.e. HTLS drive) rotate the drill bit. In this study, the energy saving analysis of the above mentioned hydrostatic drives has been performed with respect to the load profile of the blast hole drilling. In this respect, the modelling, simulation and the experimentation of the drives have been carried out. Simulations have been performed in MATLAB–Simulink environment and it has been verified through experiments. The proportional-integral-derivative control algorithm has been used to control the drives speed in various loading stages. Results show that the high-torque low-speed drive save more energy compares to the low-torque high-speed drive for the usual operating range of the blast hole drilling.
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Li, Chuangze, Benguang Han, Jie He, and Longsheng Wu. "Design of High Speed and Precision and Low-Power LVDS Driver for CMOS Image Sensor." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 2 (April 2020): 442–50. http://dx.doi.org/10.1051/jnwpu/20203820442.
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Aiming at the requirement of high speed and precision, low-power and large-capacity load of serial data interface for aerospace super large array(15k×15k) CMOS image sensor, a design scheme low voltage differential signal (LVDS) driver by combining the split-length method with the pre-emphasis technique is proposed. Firstly, comparing with the general design schemes, the present scheme uses the split-length compensation method to increase effectively the unity-gain bandwidth while keeping the op-amp gain constant. Secondly, the pre-emphasis technique is used to compensate the LVDS driver for high-frequency components to improve the driving capability of the capacitive load and high speed signal integrity (SI). The simulation results show that the accuracy of the common-mode feedback voltage is improved by using the split-length compensation method, and also the common-mode voltage changes below 15 mV. The pre-emphasis technique is used to enhance the amplitude of the high-frequency components lost during the high-speed transmission. The quality of the signal eye diagram during high-speed transmission reduces the bit error rate, and both the transmission rate and the driving load capacity are two times more than the general design (1.2 Gb/s@12 pF), and the quiescent current consumption is only 4.6 mA@12 pF. The present LVDS driver design is implemented in a typical CMOS process of 0.18 μm.
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Sofwan, Agus, M. Febriansyah, and Sugeng Sugeng. "OPERATIONAL COST REDUCTION OF GAS-THERMAL POWER PLANT BASED ON BAT ALGORITHM." SINERGI 25, no. 2 (February 20, 2021): 185. http://dx.doi.org/10.22441/sinergi.2021.2.010.
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An optimised operation of a thermal power plant is required to optimise fuel consumption cost. It is still high and becomes a problem of economic dispatch in the operation of the plant. Load scheduling and generator capacity are needed to get optimal plant operation, especially energy usage. This paper presented a thermal power plant operation analysis to obtain optimum operational energy costs using the Bat Algorithm (BA). The actual data of 6 thermal power plants to serve the peak loads in 2018 is used for the calculation. The problem solution is simulated and calculated using maximum (95%) capacity and the BA method. The Simulation is done by using MATLAB software. The generator unit and generator load characteristics are collected to obtain objective functions and constraint functions. BA completes this function to get the lowest energy. The BA method will be compared with the calculation of real-time energy generation without BA to analyse its accuracy. The total operational cost of the actual power plant without BA is $ 1,988,410. BA simulation gave the total energy cost is $1,653,374. So, the generated energy savings is 16.85%, or 335,036 MW reduction.
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Hadad, Hadad S., Ibrahim M. Metwally, and Sameh El-Betar. "Cyclic Behavior of Braced Concrete Frames: Experimental Investigation and Numerical Simulation." Building Research Journal 61, no. 2 (March 1, 2015): 101–14. http://dx.doi.org/10.2478/brj-2014-0008.
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Abstract RC shear walls have been widely used as the main lateral-load resisting system in medium and high-rise buildings because of their inherent large lateral stiffness and load resistance. But, in general, the energy dissipating capacity of RC shear walls is not very good and it has been found that using the bracing system gives good results. The main purpose of this paper is to study the effect of different types of bracing on the lateral load capacity of the frame. Also, the research contains a comparison between the braced and infilled frames to decide on the best system. The research scheme consists of four frames; the bare frame, two frames the first of which was braced with concrete, the second was braced with steel bracing and the fourth frame was infilled with solid cement bricks. All the specimens were tested under cyclic loading. The results gave some important conclusions; braced and infilled bare frames increased the lateral strength of the bare frame depending on the type of bracing and infill. Also, the different types of bracing and the infill increased the initial stiffness of the bare frame by a reasonable value. The energy dissipation for the braced and infilled frames is always higher than that for the bare frame up to failure. Also, numerical modeling was carried out with the nonlinear software platform (IDARC). The numerical results obtained with the calibrated nonlinear model are presented and compared with the experimental results. Good agreement was achieved between the numerical simulation and the test results.
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Song, Dongdong, Yingxin Yang, and Haitao Ren. "Study on Composite Design Suitable for High Hardness and Strong Abrasive Formation." Journal of Advanced Thermal Science Research 8 (December 17, 2021): 41–49. http://dx.doi.org/10.15377/2409-5826.2021.08.5.
Full textAbstract:
PDC (Polycrystalline Diamond Compact bit) composite is the most important cutting element of petroleum bit, which performance directly affects the service effect and service life of the bit. During the drilling process, the cutter will produce a large amount of friction heat when cutting the rock, resulting in a sharp increase in the internal temperature of the cutter. When the temperature reaches a certain value, thermal wear and tear are very easy to occur, which will not only cause diamond delamination but also reduce the wear resistance of the cutter. Under the action of impact load, impact failure is more likely to occur, which greatly reduces the service life of the cutter and the rock-breaking efficiency of the drill bit. Therefore, this paper studies the composite interface suitable for high-temperature drilling through the changes of cutting tooth temperature field and stress field with different interface shapes, which shows that the non-planar interface is more suitable for improving the cutting tooth life of composite under the action of comprehensive stress field.
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Li, Wanzhong, Chong Deng, Yingqiang Xu, Jian Sun, Yazhou Feng, and Duanyin Zhu. "Research on Real Surface Stability of Cone Bit Sliding Bearing Under Repeated Contact Condition." E3S Web of Conferences 299 (2021): 01006. http://dx.doi.org/10.1051/e3sconf/202129901006.
Full textAbstract:
The cone bit is the most principal rock breaking tool in drilling engineering. The statistical analysis of field data shows that the early damage and failure of sliding bearing is one of the main reasons that affect the service life and performance of the cone bit in the real drilling process. Aiming at the complex working environment of cone bit sliding bearing with heavy load, high temperature and mixed lubrication, the paper establishes a multilevel line contact model of rough surface and carries out the finite element modeling and analysis from the perspective of contact mechanics. Then the Von Mises stress, Residual normal deformation and Inelastic dissipated energy are obtained under the different cycles of loading-unloading. The results show that with the increase of cycles of loading-unloading, the part of edge area of the line contact enters into elastic shakedown and the asperities in the central area occur irreversible plastic deformation, which has a significant influence on the stability of the sliding bearing of the cone bit.
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Chiu, Hsien-Chin, Chun-Ming Chen, Li-Chun Chang, and Hsuan-Ling Kao. "A 5-Bit X-Band GaN HEMT-Based Phase Shifter." Electronics 10, no. 6 (March 11, 2021): 658. http://dx.doi.org/10.3390/electronics10060658.
Full textAbstract:
In this study, we propose a 5-bit X-band gallium nitride (GaN) high electron mobility transistor (HEMT)-based phased shifter monolithic microwave integrated circuit for a phased-array technique. The design includes high-pass/low-pass networks for the 180° phase bit, two high-pass/bandpass networks separated for the 45° and 90° phase bits, and two transmission lines based on traveling wave switch and capacitive load networks that are separated for the 11.25° and 22.5° phase bits. The state-to-state variation in the insertion loss is 11.8 ± 3.45 dB, and an input/output return loss of less than 8 dB was obtained in a frequency range of 8–12 GHz. Moreover, the phase shifter achieved a low root mean square (RMS) phase error and RMS amplitude error of 6.23° and 1.15 dB, respectively, under the same frequency range. The measured input-referred P1dB of the five primary phase shift states were larger than 29 dBm at 8 GHz. The RMS phase error and RMS amplitude error slightly increased when the temperature increased from 25 to 100 °C. The on-chip phase shifter exhibited no dc power consumption and occupied an area of 2 × 3 mm2.