Hysteresis Control in Pump-Controlled Systems—A Way to Reduce Mode-Switch Oscillations in Closed and Open Circuits

There is growing interest in using electric motors as prime movers in mobile hydraulic systems. This increases the interest in so-called pump-controlled systems, where each actuator has its own drive unit. Such architectures are primarily appealing in applications where energy efficiency is important and electric recuperation is relevant. An issue with pump-controlled systems is, however, mode-switch oscillations which can appear when the pressure levels in the system are close to the switching condition. In this paper, the mode-switching behavior of different generalized closed and open circuit configurations is investigated. The results show that the choice of where to sense the pressures has a huge impact on the behavior. They also show that, if the pressure sensing components are properly placed, closed and open circuits can perform very similarly, but that mode-switch oscillations still can occur in all circuits. Active hysteresis control is suggested as a solution and its effectiveness is analyzed. The outcome from the analysis shows that active hysteresis control can reduce the risk for mode-switch oscillations significantly.

Retrospective Analysis of Training Intensity Distribution Based on Race Pace Versus Physiological Benchmarks in Highly Trained Sprint Kayakers

Background Research results on the training intensity distribution (TID) in endurance athletes are equivocal. This non-uniformity appears to be partially founded in the different quantification methods that are implemented. So far, TID research has solely focused on sports involving the lower-body muscles as prime movers (e.g. running). Sprint kayaking imposes high demands on the upper-body endurance capacity of the athlete. As there are structural and physiological differences between upper- and lower-body musculature, TID in kayaking should be different to lower-body dominant sports. Therefore, we aimed to compare the training intensity distribution during an 8-wk macrocycle in a group of highly trained sprint kayakers employing three different methods of training intensity quantification. Methods Heart rate (HR) and velocity during on-water training of nine highly trained German sprint kayakers were recorded during the final 8 weeks of a competition period leading to the national championships. The fractional analysis of TID was based on three zones (Z) derived from either HR (TIDBla-HR) or velocity (TIDBla-V) based on blood lactate (Bla) concentrations (Z1 ≤ 2.5 mmol L−1 Bla, Z2 = 2.5–4.0 mmol L−1 Bla, Z3 ≥ 4.0 mmol L−1 Bla) of an incremental test or the 1000-m race pace (TIDRace): Z1 ≤ 85% of race pace, Z2 = 86–95% and Z3 ≥ 95%. Results TIDBla-V (Z1: 68%, Z2: 14%, Z3: 18%) differed from TIDBla-HR (Z1: 91%, Z2: 6%, Z3: 3%) in each zone (all p < 0.01). TIDRace (Z1: 73%, Z2: 20%, Z3: 7%) differed to Z3 in TIDBla-V (p < 0.01) and all three TIDBla-HR zones (all p < 0.01). Individual analysis revealed ranges of Z1, Z2, Z3 fractions for TIDBla-HR of 85–98%, 2–11% and 0.1–6%. For TIDBla-V, the individual ranges were 41–82% (Z1), 6–30% (Z2) and 8–30% (Z3) and for TIDRace 64–81% (Z1), 14–29% (Z2) and 4–10% (Z3). Conclusion The results show that the method of training intensity quantification substantially affects the fraction of TID in well-trained sprint kayakers. TIDRace determination shows low interindividual variation compared to the physiologically based TIDBla-HR and TIDBla-V. Depending on the aim of the analysis TIDRace, TIDBla-HR and TIDBla-V have advantages as well as drawbacks and may be implemented in conjunction to maximize adaptation.

HISTORY OF DEVELOPMENT AND MANUFACTURE OF TRACTORS AND PRIME-MOVERS BY THE STATE ENTERPRISE «KHARKIV DESIGN BUREAU OF ENGINEERING NAMED AFTER A. A. MOROZOV» AND STATE ENTERPRISE «MALYSHEV PLANT» (REVIEW ARTICLE)

The review article systematizes information and studies the history of designing tractors and prime-movers at the State Enterprise «Kharkiv Design Bureau for Mechanical Engineering named after A. A. Morozov» and their manufacture by the State Enterprise «Malyshev Plant » from the origin of such production in Kharkiv to the present time. The role of Kharkiv in providing the country with special equipment is revealed. Detailed biographical information about chief designers of this technique (B. N. Voronkov, N. G. Zubarev, M. N. Shchukin, A. I. Avtomonov, M. D. Borisyuk, A. D. Motrich, M. P. Kalugin, P. I. Sagir, B. I. Kalchenko) provided, their role in the development and improvement of designs of special-purpose machines is indicated. The main technical characteristics of basic models of tractors and prime-movers are presented. The main problems in the production of these types of equipment are mentioned. The article contains information about various modifications of AT-T, their main differences and purposes are indicated. Keywords: tractor, prime-mover, SE «Kharkiv Design Bureau of Engineering Named after A. A. Morozov», SE «Malyshev Plant», National Technical University «Kharkiv Polytechnic Institute»

Competency Level of MAPEH Teachers in Teaching Performing Arts Based on K to 12 Curriculum in Secondary Public Schools

The quality of education depends on the teacher as well as to the curriculum. As the prime movers to attain the addressed goals in the curriculum, teachers must have the desire to grow and improve through professional development and constant learning towards students ‘academic achievement. The descriptive method of research was utilized in this study to assess the competency level of the MAPEH teachers in teaching performing arts based on the K to 12 Curriculum. Results of the study revealed that majority of the respondents were females, married and 40 years old and below. They earned units/finished their master’s degree, held a teacher position, and had 10 years and below teaching experience. With regard to artistic inclinations particularly in terms of dancing, majority of them have potential in folk dance and modern dance. In terms of music, some teachers could play musical instruments skillfully such as guitar and piano/organ. They were highly competent in using assessment data, monitoring students’ data and achievement, using ICT resources for the teaching-learning process, giving feedbacks, making good use of allotted time and employing design. Individual or group experiential learning, cooperative learning, project method and collaborative activities were most commonly used strategies in teaching performing arts. Meanwhile, lack of facilities and equipment and limited seminars, workshops, and trainings attended were the common problems encountered.

Increasing the Efficiency of OEC with Use of Principle of Superposition and Thereby Increase Share of Wave Energy in Renewable Energy Resources

The quest for new renewable resources is at pinnacle in recent times. We have majorly 3 approaches Viz. [1] Finding new type of renewable resource. [2]Increase the use of already available renewable resources. [3] Increase the efficiency of prime movers so as to increase net power output by available quantity of renewable resources. This paper throws the light on unique idea of integrating the principle of superposition of waves and WEC. WEC or Wave Energy Convertor is a type of prime mover which was devised by OCEANLINX based in Australia. It basically works on compression of air column due to water column. The main drawback of wave energy is that it cannot be used in areas where waves are short and possess less energy. The new idea projected in this paper mainly addresses this issue and thus imparting the power to nations whose geographical location offers them generally short waves. Now they can also generate green energy and thus pushing world towards achieving goals of sustainable development.

Lean maintenance index: a measure of leanness in maintenance organizations

PurposeMaintenance organizations continue to be under pressure to systematically eliminate maintenance wastes and deliver services that their customers value. To this end, maintenance managers are implementing lean maintenance practices. But how does one consistently estimate the leanness of these practices in their organization? The purpose of this paper is to develop a framework for a metrics – referred to as the lean maintenance index (LMI) that can help managers estimate the leanness of maintenance practices.Design/methodology/approachBased on a comprehensive review of literature in the domain, this study identifies four factors and nineteen subfactors that are essential for the success of a lean maintenance program. A fuzzy-set-theory-based assessment framework is developed that can be used by an in-house team to measure the degree of implementation of lean maintenance practices in their organization. The authors applied the framework to a maintenance workshop that services diesel engines and other prime movers.FindingsThe framework provides maintenance managers valuable insights to help identify the strengths and weaknesses of their organization vis-à-vis their maintenance practices, thus enabling them come up with a firm action plan for future process improvements.Originality/valueThis paper adapts the concept of agility and readiness to maintenance work. A key contribution of this study is the identification of factors and subfactors that forms the basis to estimate the leanness of maintenance practices in an organization. Another contribution is its application to a large maintenance workshop that demonstrates the ease of its implementation. Future research in this area can help identify more factors and subfactors and thus improve the estimation of leanness.

Animate Prime Movers: A Prototype Based Methodology for Estimation of Renewable Power Production

The world is shifting towards renewable energy sources most notably solar and wind power. Besides these two, there are other sources of renewable power which are relatively less exploited. Among these, a rather unexplored field is that of animate prime movers. The current paper intends to present hardware prototype based methodology for evaluation of the potential of generatable power from an exercising animate prime mover – which in the current case is a male caprine subject. MATLAB environment has been used for an attempt to track the center of mass (COM) motion of the subject subsequent to its movement on a retrofitted treadmill. These COM motion trajectories can be used to evaluate the potential of generatable power – wherein the vertical COM motion upon the treadmill with an incline is compared with the corresponding COM motion on the machine when it is flat, and thus the power expended for vertical propulsion of the body is evaluated. This power is potentially generatable if the machine is kept flat and an energy harvesting mechanism is attached to it. Furthermore, the paper includes a relevant literature review section for this relatively unorthodox field.

Design of Light Weight-Low Cost Remotely Operated Underwater Vehicle

Remotely Operated Underwater Vehicles (ROV) currently have been utilized for scientific and commercial applications. Many industries are involved in developing robots in order to reduce human effort as well as increase productivity, efficiency, and monitoring. That said, the need to optimize the cost for design of ROVs became popular. In the present work, a simplified design procedure of a low cost-light-weight ROV is proposed. The design overview includes a description of the three thrusters operated by bilge pump electric motors. The ROV contains only a camera, an IMU and a GPS sensor. The ROV is wired to a control station that is equipped with a screen with a GUI, a joystick and a keyboard to monitor and control the ROV. The design is optimized to achieve a neutral buoyancy force in order to reduce the stabilizing effort during operation, hence reducing energy consumption. The drag force, lift force, drag center, lift center and fluid velocity contours are predicted using a CFD tool. Dynamic analysis including thrust and drag forces in longitudinal, vertical and yaw directions of motion are investigated to facilitate selection of the prime movers. Finally, the control strategy and electrical system description is presented. The proposed methodology proved that a satisfactory performance with an optimized design is achievable. The ROV design presented could be used in quick and low cost inspection of ships.

Modelling and Performance Analysis of Stationary Gas Turbines Operating Under Rotational Speed Transients

In order to increase the flexibility and performance of gas turbines, generally their manufacturers and research centers involved in their development are constantly seeking the expansion of their operational envelope as well as their efficiency, making the engine more dynamic, less polluting and able to respond promptly to variations in load demands. An important aspect that should be considered when analyzing these prime movers is the assessment of its behavior under transients due to load changes, which can be accomplished through the development of a detailed, accurate and effective computational model. Considering this scenario, the present work aims to develop a model for the simulation and analysis of the dynamic behavior of stationary gas turbines. The engine considered in this analysis has a nominal capacity of 30.7 MW (ISO conditions) and is composed by a two-spool gas generator and a free power turbine. The model was developed using T-MATS, an integrated Simulink/Matlab toolbox, develop by NASA. The gas turbine was evaluated under both permanent and transient regimes and each one of its component was analyzed individually. The assessment made it possible to determine the engine performance parameters such as efficiency, heat rate and specific fuel consumption and its operational limits (surge limits, stall, turbine inlet temperatures, etc.) under different load conditions and regimes. The results obtained were compared with available field data, and the relative deviations for the considered parameters were all lower than 1%.