Eco-economic excavator configuration method

Excavating processes performed frequently in building, civil and infrastructure projects are critical and costly. To define a cost-effective excavator configuration, an earthwork planner depends mostly on experience and intuition. This intuitive reasoning is often error-prone, and highly experience based. This paper presents a computational method called the Eco-Economic Excavator Configuration (E3C), which selects the most favorable configuration of a heavy duty excavator according to the earthwork package and its job conditions. E3C obtains the input data from external databases, derives the formulae involved in computing the process performance (e.g., production rate, process completion time, and profit), and instructs the earthwork manager in the best-fit excavator configuration (e.g., maximum digging depth, engine size in HP, and bucket size) for profitable operation by considering the implicit constraints and conditions exhaustively. The method identifies the best-fit PDFs of the process completion time and that of the total profit, given an excavator configuration. A test case, which was performed at a building basement excavating project, confirmed the usability and validity of the method.     

智能冷热量度系统

利用8XC552单片机及其外围电路组成冷热量度系统，并论述了该系统的工作原理、硬件及软件的组成和应用效果。     

An adaptive method for the Stefan problem and its application to endoglacial conduits

This paper concerns an adaptive finite element method for the Stefan one-phase problem. We derive a parabolic variational inequality using the Duvaut transformation. In each time-step we consider an adaptive algorithm based on a combination of the Uzawa method associated with the corresponding multivalued operator and a convergent adaptive method for the linear problem. We justify the convergence of the method. As an application we model an endoglacial conduit in which a phase change phenomenon takes place.     

Highly efficient distributed generation and high-capacity energy storage

With the growing amount of decentralized power production the design and operation of the grid has to be reconsidered. New problems include the two-way flow of electricity and maintaining the power balance given the increased amount of uncertain and fluctuating renewable energy sources like wind and solar that deliver electricity to the grid.Solution directions are the development of smart grids, demand side management, virtual power plants and storage of electricity. These are directions that, rightly so, are already attracting a lot of attention and R&D funding. In this paper critical issues are identified and specified. However, we will also explore new solution directions based on an integrative approach as proposed by the Dutch Royal Academy of Science foresight committee on renewable energy conversions. These alternative solutions include flexible coproduction and local production of chemicals and fuel that can also fulfill a storage function.     

Preparation and capacitance performance of nitrided lithium titanate nanoarrays

Nitrided lithium titanate (N-Li₄Ti₅O₁₂) nanoarrays with nanowire and nanotube structures were designed as the electrode materials of lithium-ion supercapacitor for electrochemical energy storage. Two types of TiO₂ nanoarrays were used as the precursor which involved TiO₂ nanowire array prepared by hydrothermal process and TiO₂ nanotube array prepared by anodization process. Li₄Ti₅O₁₂ nanoarrays were formed through hydrothermal reaction or sonochemical reaction of TiO₂ nanoarrays with lithium hydroxide and then calcination treatment process. Finally, N-Li₄Ti₅O₁₂ nanoarrays were formed through nitriding treatment of Li₄Ti₅O₁₂ using ammonia as nitrogen source. The electroactive N-Li₄Ti₅O₁₂ nanowire array and nanotube array exhibited the specific capacitance of 607.2 F g⁻¹ and 814.4 F g⁻¹ at a current density of 1 A g⁻¹, respectively. The corresponding capacitance retention was determined to be 92.1% and 94.2% after 1000 cycles at high current density of 5 A g⁻¹. The corresponding capacitance still kept 182.9 and 352.1 F g⁻¹ at much higher current density of 20 A g⁻¹, presenting reasonable rate capability for N-Li₄Ti₅O₁₂ nanoarrays. The improved capacitance performance of N-Li₄Ti₅O₁₂ nanotube array was ascribed to the more amount of TiN and more accessible nanotube surface area, which contributed to the improved conductivity and fast diffusion of electrolyte ions on the surface of electrode. Both N-Li₄Ti₅O₁₂ nanowire array and nanotube array with well-aligned integrative structure exhibited an excellent cycling stability during continuous charge/discharge process. Well-designed N-Li₄Ti₅O₁₂ nanoarrays with high capacitance, good cycling stability and rate capability presented the promising application as feasible electrode materials of lithium-ion supercapacitors for the energy storage.     

基于柔性铰链结构的二维微动工作台研究

重点介绍了一种基于PZT驱动的双柔性平行四连杆结构二维微动工作台.推导了柔性铰链各尺寸对固有频率的影响公式,并用有限元参数化分析方法,找到对固有频率影响较大的参数.将有限元模态分析值和实验测试结果相比较,探讨影响微动工作台动态性能的综合因素,为微动台的设计提供理论和实验依据.     

Hazard and operability (HAZOP) analysis. A literature review

Hazard and operability (HAZOP) methodology is a Process Hazard Analysis (PHA) technique used worldwide for studying not only the hazards of a system, but also its operability problems, by exploring the effects of any deviations from design conditions. Our paper is the first HAZOP review intended to gather HAZOP-related literature from books, guidelines, standards, major journals, and conference proceedings, with the purpose of classifying the research conducted over the years and define the HAZOP state-of-the-art.     

Hybrid TFET-MOSFET circuit: A solution to design soft-error resilient ultra-low power digital circuit

In this work, to increase the reliability of low power digital circuits in the presence of soft errors, the use of both III-V TFET- and III-V MOSFET-based gates is proposed. The hybridization exploits the facts that the transient currents generated by particle hits in TFET devices are smaller compared to those of the MOSFET-based devices while MOSFET-based gates are superior in terms of electrical masking of soft errors. In this approach, the circuit is basically implemented using InAs TFET devices to reduce the power and energy consumption while gates that can propagate generated soft errors are implemented using InAs MOSFET devices. The decision about replacing a subset of TFET-based gates by their corresponding MOSFET-based gates is made through a heuristic algorithm. Furthermore, by exploiting advantages of TFETs and MOSFETs, a hybrid TFET-MOSFET soft-error resilient and low power master-slave flip-flop is introduced. To assess the efficacy of the proposed approach, the proposed hybridization algorithm is applied to some sequential circuits of ISCAS’89 benchmark package. Simulation results show that the soft error rate of the TFET-MOSFET-based circuits due to particle hits are up to 90% smaller than that of the purely TFET-based circuits. Furthermore, energy and leakage power consumptions of the proposed hybrid circuits are up to 79% and 70%, respectively, smaller than those of the MOSFET-only designs.     

Soft switching based on analysis of transient and steady-state characteristics: Application to a single-ended high-frequency inverter

A single-ended resonant-type high-frequency inverter using a static induction transistor (SIT) described in this paper can be performed as a zero current switching (ZCS) operation without dc reactor. The SIT high-frequency inverter is a low-cost one which has no transformer and it would be developed for a high-intensity ultrasonic power supply and dc-dc converter. The circuit operation regions, not only ZCS but also ZCS-ZVS (zero current switching and zero voltage switching), were elucidated in the normalized plane. The characteristics of the inverter including the power control by frequency regulation were discussed. Furthermore, the switching characteristics in the transient-state were investigated. These characteristics were substantiated on the basis of the numerical analysis and experimental results.