Academic literature on the topic 'High-load BRT'
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Journal articles on the topic "High-load BRT"
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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.
Dissertations / Theses on the topic "High-load BRT"
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Bradley, Matthew John. "Ultra-efficient Bus Rapid Transit timetabling." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/75.
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Bus Rapid Transit (BRT) systems are increasingly used, particularly in the developing world, to provide low-cost, high-capacity urban mobility. An example of this trend is Bogotá’s TransMilenio BRT system, the test site for this thesis, which uses an homogeneous fleet of 18 metre long articulated buses to service 1,450,000 passenger trips per day, and which reaches a peak passenger load level of 45,000 passengers per hour per direction. The computational tools and techniques used to plan the timetables of such BRT systems are largely the same set of tools and techniques used to plan non-BRT transit systems.Unlike other transit systems, high-load BRT systems commonly run simultaneous express services, a situation that the tools developed to timetable non-BRT transit systems were not specifically designed for. Due to the running of simultaneous express services, the timetabling of highload BRT systems becomes a combinatorial problem, a far more complex class of problem than normal non-combinatorial timetabling. The thesis is advanced here that high-load BRT systems could be timetabled far more efficiently via a software tool built around a recognition of the problem’s combinatorial nature.This thesis is tested by building such a software tool, using that tool to develop an alternative timetable for the Américas Line of the TransMilenio BRT system, and then comparing that timetable’s performance to the performance of the existing timetable. Data used for the Américas Line was from the period Monday the 23rd to Friday the 27th of May 2005. The software tool developed to process this data changes express service stopping patterns as quickly as passenger load changes, leading to a great many express patterns over the course of a one day timetable. Due to this rapid tracking of passenger load, the resulting timetable is referred to as an “ultra-efficient timetable.”The ultra-efficient timetable produced for the Américas Line has 88 unique stopping patterns, compared to the existing timetable’s three, and is shown to be tracking passenger load far more precisely. Bus fleet size under the ultra-efficient timetable is 9% lower than for the existing timetable, indicating an estimated capital cost saving for the Américas Line of US$1.8 million. Bus kilometres travelled under the ultra-efficient timetable are 40% lower than for the existing timetable, indicating an estimated annual operating cost saving for the Américas Line of US$6 million.The ultra-efficient timetable delivering these performance improvements is shown to be approximately ten times more complex than could be reasonably deployed using paper timetables. Consequently, an ultra-efficient timetable would need to be deployed in conjunction with a fully-automated passenger information system. With this caveat, the thesis that high-load BRT systems can be far more efficiently timetabled using a combinatorial software tool is confirmed here. As an alternative to deploying ultra-efficient timetables, the combinatorial timetabling technology developed for this thesis could also be used to produce more efficient versions of normal paper-based BRT timetables.
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Hsu, Chia-Hsin, and 徐嘉欣. "High Efficiency Buck Converter with Wide Load Current Range Using Dual-mode of PWM and PSM and A 12-bit 100 MS/s Current Steering DAC Using Dynamic Element Matching and Return to Zero Techniques." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/d652de.
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碩士國立中山大學
電機工程學系研究所
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The Implementation of Signal Processing Chips”. Particularly, these topics applied the photonic gyro system are high-efficiency buck converter with wide load current range using dual-mode of PWM and PSM and 12-bit 100 MS/s current steering DAC using dynamic element matching and return to zero techniques. They are implemented using TSMC 0.35 um Mixed-Signal 2P4M Polycide 3.3/5 V and TSMC 45 nm CMOS LOGIC General Purpose Superb (40G) ELK Cu 1P10M 0.9/2.5 V processes, respectively. The proposed high efficiency buck converter is featured with integration of PWM and PSM modes to increase the efficiency given a wide load current range. The peak efficiency is 96.76 % when the load current is 1000 mA, while the efficiency in the load current range from 10 mA to 1000 mA is over 94.80 %. In addition, the proposed design accurately switches between heavy load current and light load current by a well-designed logic decoder circuit. A dynamic element matching and return to zero techniques are used to realize a 12- bit 100 MS/s current steering DAC with a precision of 1 to 10◦/h for the Heterogeneous Silicon Photonics Gyroscope. A pseudo-random number generator carries out the random selection of current sources to reduce the mismatch among these current sources caused by layout issues and also reduce the delay by using compact return to zero technique. Not only is the circuit area greatly reduced, the SFDR is also enhanced to 61 dB at 100 MS/s.
Books on the topic "High-load BRT"
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Jeffares, Ben, and Kim Sterelny. Evolutionary Psychology. Edited by Eric Margolis, Richard Samuels, and Stephen P. Stich. Oxford University Press, 2012. http://dx.doi.org/10.1093/oxfordhb/9780195309799.013.0020.
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The article presents several models of evolutionary psychology. Nativist evolutionary psychology is built around a most important insight that ordinary human decision-making has a high cognitive load. Evolutionary nativists defend a modular solution to the problem of information load on human decision-making. Human minds comprises of special purpose cognitive devices or modules. One of the modules is a language module, a module for interpreting the thoughts and intentions of others, another is a ‘naive physics’ module for causal reasoning about sticks, stones, and similar inanimate objects, a natural history module for ecological decisions, and a social exchange module for monitoring economic interactions with peers. These modules evolved in response to the distinctive, independent, and recurring problems faced by the ancestors. Domain specific modules handle information about human language, human minds, inanimate causal interactions, the biological world, and other constant adaptive demands faced by human ancestors. Nativist evolutionary psychologists have turned to moral decision making, arguing that cross-cultural moral judgments are invariant in an unexpected way. Natural selection can build and equip a special purpose module only if the information an agent needs to know is stable over evolutionary time. Automatized skills are an alternative means of coping with high-load problems. These skills are phenomenologically rather like modules, but they have very different developmental and evolutionary histories.
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Hughes, Jim. Distal femur and knee. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198813170.003.0014.
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The knee is one of the main load-bearing joints of the body, and injuries to it can involve damage to the joint or articular surfaces, or fractures to the long bones in case of high-energy trauma. The position of the contralateral leg can cause difficulty in positioning for imaging, but good positioning and technique should allow demonstration of the region for intervention. This chapter covers a selection of orthopaedic procedures involving the distal femur and knee, covering distal femoral plating and LISS plates, tension band wiring of the patella, and cerclage wiring of the patella. Each procedure includes images that demonstrate the position of the C-arm, patient, and surgical equipment, with accompanying radiographs demonstrating the resulting images.
Book chapters on the topic "High-load BRT"
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Chatterjee, Ahan. "A Decadal Walkthrough on Energy Modelling for Cloud Datacenters." In Impacts and Challenges of Cloud Business Intelligence, 195–204. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-5040-3.ch012.
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Cloud computing is the growing field in the industry, and every scale industry needs it now. The high scale usage of cloud has resulted in huge power consumption, and this power consumption has led to increase of carbon footprint affecting our mother nature. Thus, we need to optimize the power usage in the cloud servers. Various models are used to tackle this situation, of which one is a model based on link load. It minimized the bit energy consumption of network usage which includes energy efficiency routing and load balancing. Over this, multi-constraint rerouting is also adapted. Other power models which have been adapted are virtualization framework using multi-tenancy-oriented data center. It works by accommodating heterogeneous networks among virtual machines in virtual private cloud. Another strategy that is adopted is cloud partitioning concept using game theory. Other methods that are adopted are load spreading algorithm by shortest path bridging, load balancing by speed scaling, load balancing using graph constraint, and insert ranking method.
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Chatterjee, Sujit, Rubi Baishya, Debashis Saikia, and Banty Tiru. "Development of a Visible Light Communication System for Electrocardiogram Signal Transfer in Biomedical Applications." In Advances in IT Standards and Standardization Research, 50–67. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-9795-8.ch005.
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The visible light communication (VLC) system is expected to share the load on internet and communication technology (ICT) and be a promising green mode of communication, especially in healthcare applications. In this chapter, a frequency shift keying (FSK)-based VLC system is proposed that caters to the need of biomedical signal transfer. The system is implemented in hardware and is found to be flicker free to bit rates as low as 34bps and shows 82.33% improvement in BER compared to OOK. Using this method, different types of ECG signal are transferred successfully through a 1 W LED through a distance of 3m. The received signal retains the characteristics in terms of the RR interval and beats per minute (BPM) and the correlation between the transmitted and the received is very high (~100%), which is highly desired in transfer of biomedical signals. Future implementations and scope are also discussed in the chapter.
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Joshi, Tanuj, Ravikant Sharma, Vinod Mittal, and Vikas Gupta. "Finite Element Modeling and Comparative Analysis of Multiple Biocompatible Titanium Alloys for Hip Prosthesis." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220739.
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In present work, the performance of different material combinations under the peak load is analyzed using finite element code. A liner isotropic titanium implant materials and PMMA materials are utilized for an implant and bone cement respectively. However, cortical and cancellous bone are treated as non-isotropic in nature. The main objective of this work is to discover the best-suited implant material for hip replacement. Stress, strain and deformation are some of the essential parameters, to check their functionality and biomechanical performance. Finite element study demonstrates that Ti-6Al-7Nb demonstrate bet-ter results, i.e., minimum stress, deformation, and strain as compared to other material combinations. However, Ti-35Nb-7Zr-5Ta demonstrates approximately similar results as shown by Ti-6Al-7Nb. The final simulated out-comes show that Ti-6Al-7Nb material is the most suitable biocompatible material for implantation due to its lower modulus and high compatibility with the bone.
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Deniz Karaoglan, Aslan, Deniz Perin, and Kemal Yilmaz. "Design Optimization of 18-Poled High-Speed Permanent Magnet Synchronous Generator." In Artificial Intelligence. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106987.
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The aim of this research is to optimize the design of an 18-poled 8000 rpm 7 kVA high-speed permanent magnet synchronous generator. The goal is to find the best factor levels for the design parameters, namely magnet thickness (MH), offset, and embrace (EMB) to optimize the responses namely efficiency (%), rated torque (N.m), air-gap flux density (Tesla), armature current density (A/mm2), armature thermal load (A2/mm3). The aim is to keep the air-gap flux density at 1 tesla while maximizing efficiency and minimizing the rest of the responses. Optimization was carried out with one sample algorithm selected from each of the commonly used optimization algorithm classifications. For this purpose, different class of well-known optimization techniques such as response surface methodology (gradient-based methods), genetic algorithm (evolutionary-based algorithms), particle swarm optimization algorithm (swarm-based optimization algorithms), and modified social group optimization algorithm (human-based optimization algorithms) are selected. In the Ansys Maxwell environment, numerical simulations are carried out. Mathematical modeling and optimizations are performed by using Minitab and Matlab, respectively. Confirmations are also performed. Results of the comparisons show that modified social group optimization and particle swarm optimization algorithms a bit outperform the response surface methodology and genetic algorithm, for this design problem.
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Angelopoulos, Pavlos, Konstantinos Mylonas, Grigorios Tsigkas, Elias Tsepis, Evdokia Billis, and Konstantinos Fousekis. "Blood Flow Restriction Training in Cardiovascular Disease Patients." In Recent Advances in Sport Science [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96076.
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Over the past two decades, blood flow restriction training (BFRT) has gained popularity not only in athletic performance training, but also with many researchers and physical therapists as an innovative rehabilitation tool. Blood flow restriction (BFR) exercise is a novel exercise modality in clinical settings, which induces muscle hypertrophy and increases strength with low to moderate training intensity through increased anabolic processes mediated by BFR (usually with cuff inflation). BFR limits arterial and venous blood flow and leads to blood pooling, which could increase the effects of exercise-induced training. Strength training at lower intensities (20–40% of maximum strength) in combination with BFR showed similar effects on muscle hypertrophy as training at 70% strength level without BFR. In this context, considering that periods of immobilization (or reduced functionality) due to pathology, injury, or surgery cause harmful effects on muscle mass and strength in both young and old people, muscular adaptations of occlusion exercise could be beneficial to the elderly and post-operative patients in rehabilitation regarding muscle regeneration. Furthermore, as this type of exercise does not require high loads, it might be a feasible method in cardiac rehabilitation. Therefore, this chapter aims to review all recent literature regarding the impact of low-load BFR resistance training in patients with cardiovascular pathologies on muscle strength and hypertrophy, vascular function, safety, cardiovascular responses, and inflammatory markers.
Conference papers on the topic "High-load BRT"
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Liu, Jun, Dan Ma, Xianjie Wan, Weidong Yang, and Dongbing Fu. "A Design of 16-bit High Speed DAC with Segmented R2R Load." In 2020 IEEE 15th International Conference on Solid-State & Integrated Circuit Technology (ICSICT). IEEE, 2020. http://dx.doi.org/10.1109/icsict49897.2020.9278243.
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Hol, Jan. "Improved Reliability of Buckling Load Calculations using Multi-Level High-Fidelity Analysis." In 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference
14th AIAA/ASME/AHS Adaptive Structures Conference
7th. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2006. http://dx.doi.org/10.2514/6.2006-2029.
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Lai, Yi-Shao, Jenn-Ming Song, Hsiao-Chuan Chang, and Ying-Ta Chiu. "Characterizations of Ball Impact Responses of Tin-Silver-Copper Solder Joints Doped With Nickel or Germanium." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41232.
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The ball impact test (BIT) was developed based on the demand of a package-level measure of the board-level reliability of solder joints in the sense that it leads to brittle intermetallic fracturing, similar to that from a board-level drop test. The BIT itself stands alone as a unique and novel test methodology in characterizing strengths of solder joints under a high-speed shearing load. In this work, we present BIT results conducted at an impact velocity of 500 mm/s on Sn-4Ag-0.5Cu, Sn-1Ag-0.5Cu, Sn-1Ag-0.5Cu-0.05Ni, Sn-1.2Ag-0.5Cu-0.05Ni, and Sn-1Ag-0.5Cu-0.05Ge package-level solder joints, bonded on substrate pads of immersion tin (IT) and direct solder on pad (DSOP) surface finishes. Differences of BIT results with respect to multi-reflow are also reported.
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Seo, Dong Cheol, Tanvir Sayeed, M. Hasanat Zaman, and Ayhan Akinturk. "Wave Load Prediction on a Stationary Bergy Bit Near a Fixed Offshore Platform." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62392.
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Offshore oil and gas operations conducted in harsh environments such offshore Newfoundland may pose additional risks due to collision of smaller ice pieces and bergy bits with the offshore structures, including their topsides in the case of gravity based structures particularly in extreme waves. In this paper, CFD (Computational Fluid Dynamics) prediction for wave loads acting on a bergy bit around a fixed offshore platform is presented. Often the vertical column of a gravity based structure is designed against ice collisions, if operating in such an environment. In practices, topsides are usually protected by being placed sufficiently high from the still water level, away from the reach of the bergy bits. This vertical clearance between the still water level and the topside deck is known an air gap. Hence, the amount of the air gap planned for such an offshore structure is an important factor for the safety of the topsides at a given location. In this study a CFD method is applied to estimate the dynamic response of the bergy bit and provide a reliable air gap to reduce the potential risk of the bergy bit collision. In advance of more complex collision simulations using a free-floating ice for the airgap design, CFD analysis of wave load prediction on a stationary bergy bit is carried out and reported in this paper. In the experiments and CFD simulations, the location of the bergy bit is changed to quantify the change of wave load due to the hydrodynamic interaction between the bergy bit and the platform. Finally, the results of the CFD simulations are compared with the relevant experiment results to confirm the simulation performance prior to the free floating bergy bit simulations.
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Sugiura, Junichi, Steve Jones, and Paul Pastusek. "A Systematic Photo Documentation of Drill Bit Forensics Applied to Motor Back-Drive Dynamics Case Caused by Auto-Driller Dysfunction and Formation Effect." In SPE Annual Technical Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/210466-ms.
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Abstract North America shale drilling is a fast-paced environment where downhole drilling equipment is pushed to the limits for maximum rate of penetration (ROP). Downhole mud motor power sections have rapidly evolved to deliver more horsepower and torque, resulting in different downhole dynamics, such as motor back-drive drilling dynamics. This paper investigates the root cause of the motor back-drive dynamics and the bit/BHA damage caused by this. High-frequency (HF) compact drilling dynamics recorders embedded in the mud motor bit box and top sub provide unique measurements to fully understand the reaction of the power section under load relative to the type of rock being drilled. 3-axis shock, gyro and temperature sensors placed above and below the power section measure the dynamic response of power transfer to the bit and associated losses caused by motor back-drive dynamics. Formations with high interfacial severity pose more of a challenge due to the rapid change in formation strength. The torsional energy stored and released in the drill string can be high due to surface rotation-speed/torque output and downhole mud-motor speed/torque. Torsional drill string energy wind-up and release results in variable power output at the bit, inconsistent ROP and rapid fatigue on downhole equipment. Detailed analysis of the high-frequency embedded downhole sensor data as well as Electronic Drilling Recorder (EDR) data provides an in-depth understanding of mud motor dynamics. In one of the "Delaware Basin" field examples from Loving County, Texas, the root cause of the motor back-drive dynamics was identified. A systematic photo documentation of drill bit forensics was performed to precisely document the bit damage from this type of drilling dynamics. The auto-driller weight-on-bit (WOB) and ROP setpoints were examined along with the downhole sensor data and EDR to pinpoint the root cause of drilling dysfunction. A drillstring analytical model was used to predict the torsional natural frequencies, which are compared against the sensor-observed torsional oscillation frequencies. This paper reports a unique case of motor back-drive drilling dynamics caused by auto-driller dysfunction and formation effects. Additionally, a systematic photo documentation of drill bit forensics was applied to thoroughly document motor driven bit damage.
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Hohl, Andreas, Danial MacFarlane, David Selvaag Larsen, Kjetil Olsnes, Sergiy Grymalyuk, Matthias Gatzen, and Sigve Hovda. "Utilizing Downhole Sampled High-Frequency Torsional Oscillation Measurements for Identifying Stringers and Minimizing Operational Invisible Lost Time ILT." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205993-ms.
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Abstract Horizontal drilling has been the industry standard for oil production wells in the North Sea for decades. Significant improvements have been made in the precision of directional drilling by rotary steerable systems (RSS), nevertheless there remain opportunities to mitigate operational challenges in complex drilling environments. One such challenge is the occurrence of hard stringers interbedded between soft sandstone and limestone formations within the reservoirs. The interaction between the bit and hard stringers at the interfaces can lead to a deflection of the bit, resulting in high local doglegs (HLDs), and excessive static loads unless mitigation actions are triggered in a timely fashion. Operational parameters have to be adjusted during hard-stringer drilling, but are also constrained in the underlying formation to avoid HLDs and guarantee bit and BHA integrity. The key to efficient stringer drilling presented here is a consistent, timely and reliable method of detecting stringers. This is enabled by a fit for purpose stringer detection algorithm embedded in a measurement-while-drilling (MWD) tool for vibration and load measurements, combined in a systems approach with an automated surface system. Different indicators such as vibrations, loads and ROP that are traditionally used for stringer detection have been analyzed in the development phase of the algorithm. High-frequency torsional oscillations (HFTO) have been found to be a leading indicator for stringer drilling: HFTO is a torsional vibration phenomenon with high frequencies (50Hz-450Hz) and is only excited by the bit-rock interaction in hard formations. The HFTO amplitudes in sand/lime stones and calcite stringers show well separated distributions. Finally, HFTO is unique in that it is not directly affected by the driller, or due to other downhole dysfunctions, e.g. compared to a change in weight on bit (WOB) which may be caused by a surface parameter change or a stabilizer. The physics-based algorithm embedded in the MWD tool combines tangential acceleration and dynamic torque measurements to calculate the maximum HFTO load in the BHA. A stringer is identified if an HFTO maximum amplitude threshold is exceeded and the energy is localized in one frequency. The downhole indicator is aggregated to a 1-bit value (stringer/no stringer) that enables a high telemetry update rate and thereby a timely reaction at surface. The stringer indicator and advice are displayed to the driller and are actively used for stringer drilling. The paper describes the technology as well as the operational setup, and experience from the first field deployments. By using the new technology, the driller can react faster to any stringer and use appropriate parameters to avoid costly HLDs. First field deployments demonstrate a significant improvement in invisible lost time (ILT) caused by deflections of the bit, resulting in a considerable reduction in well delivery costs.
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Cayeux, Eric, and Hans Joakim Skadsem. "Estimation of Weight and Torque on Bit: Assessment of Uncertainties, Correction and Calibration Methods." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23866.
Full textAbstract:
The efficiency of a drilling operation is to a great extent governed by how well one is able to optimize the rate of penetration (ROP) throughout each stage of the operation. ROP optimization normally involves balancing drilling speed on the one hand with acceptable wear to the drill bit on the other. The bit lifetime is largely determined by the mechanical conditions at the bit-formation rock interface and the weight on bit (WOB) and torque on bit (TOB) provide important information related to the working condition of the bit. The accuracy of WOB and TOB measurements can thus become a determining factor for the overall drilling efficiency. Due to the low bandwidth of downhole mud pulse-based telemetry systems, the WOB and the TOB are generally derived from surface measurements, i.e. from the hook load and the top-drive torque. Field experience indicates that a WOB derived from surface measurements can be of limited accuracy, such as when surface measurements suggest a negative WOB even though the ROP is positive, or when high sampling rate and high precision downhole measurements confirm a large discrepancy between the memory recorded downhole data and the estimated values based on the measurements made at the level of the hoisting equipment and the top-drive. The reason for these inconsistencies is simply that there are numerous physical processes taking place between the bit and the surface measurements that are normally not accounted for when WOB and TOB are estimated. This paper reviews and analyses the sources of these deviations and models the physical processes in order to quantify the precision for which the WOB and the TOB can be ascertained using solely surface measurements. Methods are also proposed that compensate for certain side effects by utilizing real-time torque and drag and hydraulic calculations.
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Li, Yousun, Heedo Yun, Jane Q. Zhang, Shankar Bhat Aramanadka, and Heping Zhang. "Dynamic and Frictional Interaction Between Buoyancy Can Riser Tensioner System and SPAR Hull." In ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67143.
Full textAbstract:
Buoyancy Can Riser Tensioner (BCRT) systems provide tension to the Top Tensioned Riser (TTR) systems. The main benefit of employing BCRT is that it can minimize the interaction between the floating platform and riser system. The possible lateral impact and dynamic loads which may occur between the SPAR hull and BCRT are minimized by placing the so-called Compliant Guides (CGs) at the sliding interfaces. The CGs are designed to allow relatively free sliding of the BCRT in the riser axial direction, while preventing/minimizing lateral impact loads by providing lateral compliance. CGs are made of high stiffness and abrasion resistant material, such as elastomer materials. Objective of this study is to develop a numerical capability and analysis procedure to evaluate the spar-riser interaction mechanism and their effects on spar motion and riser response. The newly developed frictional interface element is an essential component of an FE model for the time simulation of the coupled motions of SPAR and riser systems. The algorithm can be used to investigate the dynamic and frictional interaction between the SPAR and BCRTs, such as the friction’s impact on the SPAR motion and riser stresses, and the dynamic load/wear requirements on the CGs.
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Tikhonov, Vadim S., Alexander I. Safronov, and Michael Ya Gelfgat. "Investigation of Drillstring Transverse Vibrations at Rotary Drilling of Inclined Wells." In ASME 2002 Engineering Technology Conference on Energy. ASMEDC, 2002. http://dx.doi.org/10.1115/etce2002/drill-29031.
Full textAbstract:
Significant part of axial compression load transferred to the bit while drilling of wells with high zenith angles is resisted by service drill pipes. By the action of static critical load, buckling of drillstring occurs initially in the shape of a sinusoid and subsequently, as the load increases, in the shape of a helix. Drillstring rotation promotes the occurrence of critical modes. As a result the drillstring can start snaking motion at the low side of the hole. When the rotary speed grows, whirling of the drillstring can occur with axial load much lower than the buckling load. In this paper, a nonlinear mathematical model of lateral vibrations of a rotating drillstring in straitened space of a straight inclined hole is proposed. A numerical method to solve drillstring motion equations has been developed that allowed to reduce time of computation. This made it possible to conduct a detailed study of how the main drilling parameters (compression load, drillstring rotary speed, hole angle, friction factor, etc.) effect drillstring motion in the well. Results of the study may be used to choose drillstring operation modes for rotary drilling of inclined and horizontal wells.
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Hohl, Carsten, Sven-Hendrik Joerns, Sasa Mihajlovic, Ingo Roders, and Christian Wille. "Near Bit Load Sensing in RSS Applications." In International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22037-ea.
Full textAbstract:
Abstract Direct feedback from the drilling process will be key to enhance overall drilling performance further, improve steering and will help detect drilling dysfunctions early. This is especially true for demanding drilling applications, such as drilling in difficult geological formations. Faults, hard stringers or borehole instabilities can have a negative impact on rate of penetration (ROP) or even worse can damage equipment and cause non-productive time (NPT). This gets pronounced for extended reach drilling, where long drill strings delay the received feedback from the drilling process or effects along the drill string (e.g friction) skew the results. To overcome these obstacles a near bit sensor was developed to provide real time weight-on-bit (WOB), torque-on-bit (TOB), bending and bending orientation data. It is directly integrated into the steering unit of the rotary steerable system (RSS) with the goal to be simplistic, cost efficient and robust. To discuss potential uses and limitations of the load sensor, the basic design and operational principle are shown. Different usage scenarios of the system are presented in theoretical terms and backed by real-world data. One scenario is the possibility to diagnose reasons for low ROP, for instance weight transfer issues can be distinguished from bit damages if WOB and TOB real time data is available. For early detection of unwanted deflections in directional drilling, for instance due to faults or tilted beds, near bit bending and bending orientation measurements of the RSS system can be used. The near bit sensor design proves to be reliable and cost efficient. It shows high potential to increase ROP and reduce NPT and overall drilling cost.
Reports on the topic "High-load BRT"
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Bao, Jieyi, Xiaoqiang Hu, Cheng Peng, Yi Jiang, Shuo Li, and Tommy Nantung. Truck Traffic and Load Spectra of Indiana Roadways for the Mechanistic-Empirical Pavement Design Guide. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317227.
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The Mechanistic-Empirical Pavement Design Guide (MEPDG) has been employed for pavement design by the Indiana Department of Transportation (INDOT) since 2009 and has generated efficient pavement designs with a lower cost. It has been demonstrated that the success of MEPDG implementation depends largely on a high level of accuracy associated with the information supplied as design inputs. Vehicular traffic loading is one of the key factors that may cause not only pavement structural failures, such as fatigue cracking and rutting, but also functional surface distresses, including friction and smoothness. In particular, truck load spectra play a critical role in all aspects of the pavement structure design. Inaccurate traffic information will yield an incorrect estimate of pavement thickness, which can either make the pavement fail prematurely in the case of under-designed thickness or increase construction cost in the case of over-designed thickness. The primary objective of this study was to update the traffic design input module, and thus to improve the current INDOT pavement design procedures. Efforts were made to reclassify truck traffic categories to accurately account for the specific axle load spectra on two-lane roads with low truck traffic and interstate routes with very high truck traffic. The traffic input module was updated with the most recent data to better reflect the axle load spectra for pavement design. Vehicle platoons were analyzed to better understand the truck traffic characteristics. The unclassified vehicles by traffic recording devices were examined and analyzed to identify possible causes of the inaccurate data collection. Bus traffic in the Indiana urban areas was investigated to provide additional information for highway engineers with respect to city streets as well as highway sections passing through urban areas. New equivalent single axle load (ESAL) values were determined based on the updated traffic data. In addition, a truck traffic data repository and visualization model and a TABLEAU interactive visualization dashboard model were developed for easy access, view, storage, and analysis of MEPDG related traffic data.
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Wang, Wei, Michael Brown, Matteo Ciantia, and Yaseen Sharif. DEM simulation of cyclic tests on an offshore screw pile for floating wind. University of Dundee, December 2021. http://dx.doi.org/10.20933/100001231.
Full textAbstract:
Screw piles need to be upscaled for offshore use e.g. being an alternative foundation and anchor form for offshore floating wind turbines, although the high demand of vertical installation forces could prevent its application if conventional pitch-matched installation is used. Recent studies, using numerical and centrifuge physical tests, indicated that the vertical installation force can be reduced by adopting over-flighting which also improved axial uplift capacity of the screw pile. The current study extends the scope to axial cyclic performance with respect to the installation approach. Using quasi-static discrete element method (DEM) simulation it was found that the over-flighted screw pile showed a lower displacement accumulation rate, compared to a pitch-matched installed pile, in terms of load-controlled cyclic tests. Sensitivity analysis of the setup of the cyclic loading servo shows the maximum velocity during the tests should be limited to avoid significant exaggeration of the pile displacement accumulation but this may lead to very high run durations.
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Pag, F., M. Jesper, U. Jordan, W. Gruber-Glatzl, and J. Fluch. Reference applications for renewable heat. IEA SHC Task 64, January 2021. http://dx.doi.org/10.18777/ieashc-task64-2021-0002.
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There is a high degree of freedom and flexibility in the way to integrate renewable process heat in industrial processes. Nearly in every industrial or commercial application various heat sinks can be found, which are suitable to be supplied by renewable heat, e.g. from solar thermal, heat pumps, biomass or others. But in contrast to conventional fossil fuel powered heating systems, most renewable heating technologies are more sensitive to the requirements defined by the specific demand of the industrial company. Fossil fuel-based systems benefit from their indifference to process temperatures in terms of energy efficiency, their flexibility with respect to part-load as well as on-off operation, and the fuel as a (unlimited) chemical storage. In contrast, the required temperature and the temporal course of the heat demand over the year determine whether a certain regenerative heat generator is technically feasible at all or at least significantly influence parameters like efficiency or coverage rate.
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Villacis, Alexis, Victor Barrera, Jeffrey Alwang, Carlos Caicedo, and James Quiroz. Strategies to strengthen Ecuador's high-value cacao value chain. Inter-American Development Bank, January 2022. http://dx.doi.org/10.18235/0003960.
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Since the early nineteenth century, cacao has been an important export earner for Ecuador. Today the importance of this sector remains, as Ecuador is the main producer and exporter of Fine and Flavor cacao worldwide. Motivated by the main transformations of the global food systems and the increasing demand for multidimensional credence attributes, this study examines the present state of Ecuador's cacao industry, identifies areas of opportunity, and discusses how the private and public sectors can work together to meet existing and emerging challenges. Findings are supported by interviews conducted with the principal actors in the Ecuadorian cacao industry and two case studies. The first case study focuses on how associativity can help cacao farmers producing high-quality beans to differentiate themselves and succeed in modern agri-food markets. The second case study explores the success of a local chocolate firm and its links with local cacao farmers. Findings suggest that market trends have created new business opportunities for cacao producers and chocolate processors. These opportunities are most open to firms who can personalize and differentiate their products, for example, through the use of quality certifications such as organic, fair trade, reduced carbon load, etc. More importantly, market developments are driving exporters to enhance the performance of cacao value chains in the country, but the sector requires coordination to capture reputation and credence-based demands for the local cacao.
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Delmer, Deborah, Nicholas Carpita, and Abraham Marcus. Induced Plant Cell Wall Modifications: Use of Plant Cells with Altered Walls to Study Wall Structure, Growth and Potential for Genetic Modification. United States Department of Agriculture, May 1995. http://dx.doi.org/10.32747/1995.7613021.bard.
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Our previous work indicated that suspension-cultured plant cells show remarkable flexibility in altering cell wall structure in response either to growth on saline medium or in the presence of the cellulose synthesis inhibitor 2,-6-dichlorobenzonitrile (DCB). We have continued to analyze the structure of these modified cell walls to understand how the changes modify wall strength, porosity, and ability to expand. The major load-bearing network in the walls of DCB-adapted dicot cells that lack a substantial cellulose-xyloglucan network is comprised of Ca2+-bridged pectates; these cells also have an unusual and abundant soluble pectic fraction. By contrast, DCB-adapted barley, a graminaceous monocot achieves extra wall strength by enhanced cross-linking of its non-cellulosic polysaccharide network via phenolic residues. Our results have also shed new light on normal wall stucture: 1) the cellulose-xyloglucan network may be independent of other wall networks in dicot primary walls and accounts for about 70% of the total wall strength; 2) the pectic network in dicot walls is the primary determinant of wall porosity; 3) both wall strength and porosity in graminaceous monocot primary walls is greatly influenced by the degree of phenolic cross-linking between non-cellulosic polysaccharides; and 4) the fact that the monocot cells do not secrete excess glucuronoarabinoxylan and mixed-linked glucan in response to growth on DCB, suggests that these two non-cellulosic polymers do not normally interact with cellulose in a manner similar to xyloglucan. We also attempted to understand the factors which limit cell expansion during growth of cells in saline medium. Analyses of hydrolytic enzyme activities suggest that xyloglucan metabolism is not repressed during growth on NaCl. Unlike non-adapted cells, salt-adapted cells were found to lack pectin methyl esterase, but it is not clear how this difference could relate to alterations in wall expansibility. Salt-adaped cell walls contain reduced hyp and secrete two unique PRPP-related proteins suggesting that high NaCl inhibits the cross-linking of these proteins into the walls, a finding that might relate to their altered expansibility.
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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman, and Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580685.bard.
Full textAbstract:
Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.
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SOUND RADIATION OF ORTHOTROPIC STEEL DECKS SUBJECTED TO MOVING VEHICLE LOADS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.052.
Full textAbstract:
Orthotropic steel decks (OSDs) are widely used in the construction of steel bridges due to their high bearing capacity and low material consumption. Current investigations into OSDs mainly focus on issues associated with static, stability, fatigue, etc. However, from the perspective of dynamics, structures with low dead loads may be susceptible to excessive vibration and noise, which occurs when shocks caused by moving traffic loads are transferred to the bridge deck and other components. Hence, bridge vibration and the associated noise are critical issues in steel bridges. This paper investigates the vibration and noise characteristics of OSDs under moving vehicle loads by using analytical method. First, the forced vibration response of the OSDs is solved by the Finite Element Method(FEM), and then the obtained response is used as the boundary condition of the OSDs boundary element model to solve the acoustic radiation. Finally, the variation rules of the vibration and sound radiation of the OSDs are analyzed when the load parameters, boundary conditions and structural parameters are changed. The results show that when analyzing the high-frequency vibration and noise of the OSDs, the all-shell-element model should be selected. The high frequency part of vibration and sound pressure of the OSDs is greater than the low frequency part under moving load. Increasing the load speed will increase the low-frequency part of vibration and sound pressure, but increasing the load eccentricity will have the opposite result. Strengthening the boundary constraints and increasing the number of ribs will suppress the vibration and reduce the sound pressure.
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FINITE ELEMENT ANALYSIS ON BEHAVIOR OF HCFHST MIDDLE LONG COLUMNS WITH INNER I-SHAPED CFRP UNDER AXIAL LOAD. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.033.
Full textAbstract:
In this paper, the behavior of high-strength concrete filled high-strength square steel tube (HCFHST) middle long columns with inner I-shaped CFRP profile under axial load was studied. The finite element analysis models were established by ABAQUS software based on reasonable material constitutive relationship models. The whole process curve of load-deformation was analyzed. In addition, effects of concrete strength, steel yield strength, slenderness ratio, steel ratio and configuration ratio of CFRP on mechanical behavior of middle long columns were studied. On the basis of the parametric analysis, the limit slenderness ratio of middle long columns was obtained. Results show that with the increase of steel yield strength, the bearing capacity increases gradually, but ductility decreases. The higher the concrete strength is, the greater the ultimate bearing capacity is. Effect of steel ratio on the ultimate bearing capacity and ductility is relatively obvious. The ultimate bearing capacity of HCFHST middle long columns with inner I-shaped CFRP profile decreases with the increase of slenderness ratio.