Efficiency Of Whole System Research Articles

The development of a high-efficiency aquaculture water pump using self-adhesive electrical steel

Traditional water pump use AC motor combines with gearbox to achieve high torque and low speed to protect fish form injury by blades, which will shorten the life of waterwheel. Besides, the efficiency of the gearbox is about 40 ∼ 50%, resulting in low efficiency of whole system, and translated into poor reliability. The waterwheel in this study uses surface permanent magnet (SPM) motor instead of AC motor. However, the design of conventional waterwheel PM motor has the following drawbacks: (a) the slot fill factor cannot be too low; (b) the spacing between the rotor magnet grooves is too large, which affect the efficiency of the motor. To improve the motor efficiency without changing the shape of the stator core, this study developed an assembled stator core to improve the slot fill rate of motor winding. However, if the stack length of the stator core is too high, there will be a problem of core breakage. Therefore, this study introduced the self-adhesive steel to develop a self-adhesive assembled stator core to improve the breakage situation, and also to take advantage of the higher slot fill rate of the assembled core. Furthermore, in order to solve the problem of large spacing between the rotor magnet grooves, we optimize the magnetic circuit design by using simulation to improve the motor performance, such as magnet size, slot opening size, etc, to make the back electromotive force waveform as a sine wave. In addition, this design also reduces the thickness of magnets to reduce the cogging torque of the motor, and effectively reduces magnet usage to reduce the cost. As a result, this study developed a high-efficiency waterwheel SPM motor about 86.32% at 123 rpm, by using self-adhesive assembled stator core to increase the slot fill factor. The overall efficiency of system reaches about 78.72%.

A hybrid MPI-CUDA approach for nonequispaced discrete Fourier transformation

Nonequispaced discrete Fourier transformation (NDFT) is widely applied in all aspects of computational science and engineering. The computational efficiency and accuracy of NDFT has always been a critical issue in hindering its comprehensive applications both in intensive and in extensive aspects of scientific computing. In our previous work Yang et al. (2018), a CUNFFT method was proposed and it shown outstanding performance in handling NDFT at intermediate scale based on CUDA (Compute Unified Device Architecture) technology. In the current work, we further improved the computational efficiency of the CUNTTF method using an efficient MPI-CUDA hybrid parallelization (HP) scheme of NFFT to achieve a cutting-edge treatment of NDFT at super extended scale. Within this HP-NFFT method, the spatial domain of NDFT is decomposed into several parts according to the accumulative feature of NDFT and the detailed number of CPU and GPU nodes. These decomposed NDFT subcells are independently calculated on different CPU nodes using a MPI process-level parallelization mode, and on different GPU nodes using a CUDA thread-level parallelization mode and CUNFFT algorithm. A massive benchmarking of the HP-NFFT method indicates that this method exhibits a dramatic improvement in computational efficiency for handling NDFT at super extended scale without loss of computational precision. Furthermore, the HP-NFFT method is validated via the calculation of Madelung constant of fluorite crystal structure, and thereafter verified that this method is robust for the calculation of electrostatic interactions between charged ions in molecular dynamics simulation systems. Program summaryProgram title: HP-NFFTCPC Library link to program files:http://dx.doi.org/10.17632/ys2y92jkwy.1Licensing provisions: GNU General Public License 3Programming language: MPI, C, and CUDA CSupplementary material: The program is designed for effective computation of large-scale nonequispaced discrete Fourier transformation (NDFT), which runs on particular computers equipped with NVIDIA GPUs. It has been tested on (a) one single computer node with Intel(R) Core(TM) i7-3770 @ 3.40 GHz (CPU) and GTX 980 Ti (GPU), and (b) MPI parallel computer nodes with the same configurations.Nature of problem: For NDFT, the computation is extremely time-consuming in many domains of computational physics due to the failure to utilize FFT directly, which often affects the computational efficiency of whole system seriously. Although the parallel method CUNFFT based on GPU has achieved a qualitative leap compared with previous methods in NDFT computation, the computation capability is limited to the throughput capacity of GPU when the size of NDFT system is big enough.Solution method: We constructed a hybrid parallel architecture, in which CPU and GPU are combined to accelerate the NDFT computation effectively. Firstly, the NDFT system is divided into several subcells via domain-decomposition method. Then MPI (Message Passing Interface) is used to implement the CPU-parallel computation with each computer node corresponding to a particular subcell, and furthermore each subcell in one computer node will be executed in GPU in parallel efficiently. In this hybrid parallel method, the most critical technical problem is how to parallelize a CUNFFT in the parallel strategy, which is conquered effectively by deep-seated research of basic principles and some algorithm skills.Restrictions: The HP-NFFT is mainly oriented to, and has shown significant computational efficiency to deal with large-scale NDFT computations. However, for a small NDFT system containing less than 10^6 particles, the mode of multiple computer nodes has no apparent efficiency advantage or even lower efficiency compared with the mode of a single computer node because of the serious network delay.

A class of bi-level vector extremum models with hybrid uncertain coefficients and its application to supply chain planning problems

Decision-making optimization for supply chain planning under uncertain environment is of vital importance since it determines the reliability and efficiency of whole system. In this paper, a bi-level supply chain planning model is established in which the core company is the leader and the suppliers and retailers are the followers in the hierarchal process. Considering the hybrid uncertainty of randomness and fuzziness in the bi-level vector extremum models, a class of linear combination between fuzzy coefficients and decision variables is studied and its crisp equivalent transformation under the given possibilistic level is proposed. Furthermore, the fuzzy decision is applied to separate the two-planner Stakelberg-Nash equilibrium and the Genetic Algorithm (GA) is developed to solve the bi-level multi-objective model with hybrid variables. A practical case is provided to illustrate robustness and practicality of the proposed methodology, and algorithm comparison is then given to prove the efficiency of the GA. The computational results indicate that the proposed model and techniques can provide appropriate tools to tackle the other supply chain planning problems with hybrid variable in uncertain decision-making environment.

Performance investigation of a new geothermal combined cooling, heating and power system

In this paper, a new geothermal combined cooling, heating and power system that integrates flash power cycle and ammonia-water absorption refrigeration cycle, is proposed to supply electricity, refrigerant water and domestic hot water simultaneously to users. In the system, the refrigeration cycle serves as the bottom cycle of the power cycle by further utilizing the exhausted geothermal water from the flasher of the power cycle, meanwhile all waste heat of the power and refrigeration cycles is recovered for supplying heat, thus effectively improving the energy conversion efficiency of whole system. This paper establishes detailed mathematical models of the proposed system and conducts a valid model validation. Then a preliminary design condition of the system is given and the results show that the exergy efficiency of system could reach 43.69% under the condition of 170 ℃ geothermal water. An exergy loss analysis is carried out based on the design condition, demonstrating that the maximal exergy destruction exists in the condenser of flash cycle, accounting for 48.53% of the total exergy destruction of the system; the components used for separating or mixing fluids including rectification column, absorber and flasher, occupying 17.68%, 9.02% and 9.30% respectively, are prone to generate exergy destructions. Finally a thermodynamic parameter analysis, in order to assess the effects of seven key parameters on the system performance, is performed. The results show that there are an optimal flash pressure (about 300 kPa) and an optimal generator temperature (about 120 ℃) respectively that could make the exergy efficiency of system maximal. Within some scopes, lower turbine back pressure and rectification column pressure, higher ammonia concentration of ammonia-strong solution, bring about higher exergy efficiency of system. Additionally the evaporation pressure and the reflux ratio of rectifier just make little difference on the exergy efficiency of system.

Design of Solar Tracking System for Capturing Maximum Amount of Solar Energy

This paper proposes a design of solar tracking system for capturing maximum amount of solar energy by rotating the solar panel. From sun rise to sun set, the sun changes its direction several times due to which the static solar panel fails to capture maximum solar energy throughout the day. Therefore, it is required to develop a system that is capable of generating electrical energy by making use of maximum amount of solar energy. This paper discloses about the rotatable solar tracking system capable of rotating along the sun direction for tracking maximum amount of solar energy. This advanced technology not only utilize the solar energy more effectively but also improves the efficiency of whole system.

Area-Saving and High-Efficiency RGB LED Driver with Adaptive Driving Voltage and Energy-Saving Technique

The red-green-blue light-emitting diode (RGBLED) driver with adaptive driving voltage and energy-saving (ADVE) technique is presented in this paper. To obtain the proper driving voltage, a dynamic output voltage selector is proposed. This approach tracks the reference voltage of a boost converter to achieve the appropriate output voltage of the boost converter. Hence, the power loss of the linear current regulator is reduced to improve the efficiency of whole system. Moreover, the chip area is saved by the proposed switching linear current regulator. This chip was fabricated using TSMC 0.35 μm 2P4M complementary metal-oxide-semiconductor (CMOS) technology. The active chip area is 0.3 mm2. The maximum driving current and operating frequency are 100 mA and 100 kHz, respectively. Compared with a conventional LED driver with fixed output voltage, the experimental results demonstrate that the power loss of the proposed LED driver with ADVE technique is reduced by over 58%.

Coupled-Inductor-Based Aalborg Inverter With Input DC Energy Regulation

Due to the global environmental issues and energy crisis, the injection of renewable energy sources (RESs) into the power system is continuously increasing. As the interface between RESs and power grid, grid-tied inverters using MOSFET switches, without traditional line frequency transformers, show some potential advantages, in terms of low cost, high efficiency, and lightweight and small size. Among several proposed configurations, the Aalborg inverter was proposed as a new family of high efficiency MOSFET-switch-based hybrid source inverters. For a conventional “half bridge” type Aalborg inverter, due to the imbalance of two independent dc sources, the input dc energies may not be fully utilized, which may reduce the efficiency of whole system. In order to extract the maximum energy from two independent dc sources, a coupled-inductor-based “half bridge” type Aalborg inverter is proposed in this paper. The principle of operation is presented and demonstrated through equivalent circuits. The effectiveness of a new energy balancing technique has been validated through simulations and experiments on a 110 V/ 500 W prototype.

Thermal performance analysis of Brayton cycle with waste heat recovery boiler for diesel engines of offshore oil production facilities

This paper presents the theoretical analysis and on-site testing on the thermal performance of the waste heat recovery system for offshore oil production facilities, including the components of diesel engines, thermal boilers and waste heat boilers. We use the ideal air standard Brayton cycle to analyse the thermal performance. In comparison with the traditional design, the fans at the engine outlet of the waste heat recovery boiler is removed due to the limited space of the offshore platform. The cases with fan and without fan are compared in terms of thermal dynamics performance, energy efficiency and thermo-economic index of the system. The results show that the application of the WHRB increases the energy efficiency of the whole system, but increases the flow resistance in the duct. It is proved that as the waste heat recovery boiler takes the place of the thermal boiler, the energy efficiency of whole system without fan is slightly reduced but heat recovery efficiency is improved. This research provides an important guidance to improve the waste heat recovery for offshore oil production facilities.

Dynamic simulation and efficiency analysis of beam pumping system

An improved whole model of beam pumping system was built. In the detail, for surface transmission system (STS), a new mathematical model was established considering the influence of some factors on the STS’s torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string (SRS), an improved mathematical model was built considering the influence of some parameters on the SRS’s longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system efficiency is sensitive to motor power, pump diameter, stroke number, ratio of gas and oil, and submergence depth. The simulation results have important significance for improving the efficiency of beam pumping system.

Developing network data envelopment analysis model for supply chain performance measurement in the presence of zero data

AbstractPerformance measurement of supply chain (SC) has a vital impact on SC management and can increase efficiency of whole system and also brings competitive advantages for companies. Conventional data envelopment analysis (DEA) models treat the supply chain as a black box and do not deal with interactions of components within supply chain. Existence of zero data in supply chains can be a new assumption in performance evaluation. The main objective of this paper is to propose a new network DEA (NDEA) model in the presence of zero data. In addition, to rank supply chains, this paper proposes a novel super‐efficiency formulation of NDEA using input saving and output surplus concepts. To demonstrate applicability of the proposed model, a case study is presented.

Moving task allocation and reallocation method based on body expansion behaviour for distributed multi-robot coordination

The inconvenience and cost of utilising existing task assignment approaches to resolve dynamical mobile task allocation. For such new domain, we first propose a method, called dynamical-sequential task allocation and reallocation, by implementing multi-round negotiation and body expansion behaviour. Every former half time step, robots negotiate sequentially and select tasks to perform, and declare the information to other robots. When all robots have finished first time selection, then the remaining unselected robots choose the remaining unassigned tasks again sequentially at the latter half time step. We set two distance thresholds for robot decision-making to apply body expansion behaviour. The advantages of our methodology are demonstrated by comparison with existing algorithms, simulation results demonstrate that the efficiency for whole system to accomplish given tasks is improved by utilising our approach. Moreover, it is more conducive to reduce the numerous computational time and communication compared with existing investigated task assignment methods.

Application of Ground Source Heat Pump to a Supermarket in Portugal

The objective of the present paper is to describe a technical and economical visibility study of the application of ground source heat pumps (GSHP) in a supermarket in Portugal. The study was developed under the European project Integration of Geothermal Energy Into Industrial Application - IGEIA, project number EIE 06/001, supported by the Intelligent Energy for Europe, IEE, of EACI, European Commission. In general for supermarkets installed in single buildings, the building envelope has higher rates of envelope areas per indoor air volume. In Portugal this fact produces high need of heating during the winter season and high cooling needs during the summer season. Inside the building there are strong internal heat loads produced by high densities of lights and equipments. However these internal loads are not distributed uniformly. There are some areas with high production of heat but there are others with production of cooling. Therefore the acclimatization of this kind of buildings is not so easy and the balance of heating and cooling needs is depending of different parameters which should be well evaluated. The energy consummation of the cold display cases and deep freezers in market area and storage is also very high. The different energy needs could be studied in an integrated way and could be partially satisfied by geothermal energy using ground source heat pumps. At the same time the boreholes could be used as an energy reservoir increasing the efficiency of whole system. Four different climatic zones in Portugal were selected, (north coast, interior north, south coast and interior south) using the same system. The results of the study show that the all energy needs can by partially satisfied by geothermal energy but they need to be integrated to increase the global efficiency. The paper shows that the geothermal energy can be an attractive application for the supermarkets in Portugal if the energy solution is studied in an integrated way and if it is also considered as a cost the emissions of CO2 avoid by the new system.

Research and application of fingerprint image quality estimation

Fingerprint image quality estimation is an important step of Automatic Fingerprint Identify System(AFIS).The quality of fingerprint image from fingerprint machine seriously affects preprocess and identification.The exiting detailed regulations were analyzed,the influence on fingerprint quality from valid area,range of gray level,dry,wet to deflect were discussed.A new method was proposed to estimate fingerprint image quality based on information about edge-minutiaes, and qualified fingerprint images were provided.Experimental results show that it can filter unqualified fingerprint image effectively,and it is helpful to raise the efficiency of whole system.

Analysis of Integrated Coal Gasifier/Molten Carbonate Fuel Cell System. Reflection of Practical Generating Performance on Overall Power Plant.

Materials and heat balance in Integrated Coal Gasification/Molten Carbonate Fuel Cell (IG/MCFC) combined system have been calculated. In the calculation, an anode recycling system and an anode heat exchange system have been studied. The condition that non-deposition of carbon in anode inlet gas and that over 1% hydrogen composition in anode outlet gas have been supposed. In the case that the value of (H2·CO2)/(CO·H2O) ratio decreased to be 0.3 times than equilibrium value, the maximum fuel utilisation of the anode recycling system evaluated to be around 80%, while the maximum fuel utilisation of the anode heat exchange system estimated to be around 90%. From the results, fuel utilisation of anode heat exchange system could be set higher than that of anode gas recycling system. The analysis code has been applied to study a relation between partial pressure of CO2 in cathode gas and thermal efficiency of whole system. By changing the cooling value of cathode gas recycling line, the partial pressure of CO2 in cathode gas could be controlled. For the purpose to keep the CO2 partial pressure of cathode gas lower than 0.1 MPa, the cooling ratio of cathode recycling line should be decreased. By decrease of cooling ratio of cathode recycling line, the difference of thermal efficiency between two discussed systems has been decreased to be 1-2%.