Design of nanoscale molecular wire based on diphenylacetylene: Role of linkage

Theoretical investigation has been performed on electron transport properties of diphenylacetylene-based molecules sandwiched between two gold surfaces. Different linkers such as sulfur, nitrogen, oxygen, CS, CO, CN, NS, NO and NN have been considered to study the role of linkage in the conduction properties of the molecular wire. The charge transfer across the metal–molecule and bonding nature at the interfacial contact are illustrated by natural bond orbital analysis. It is found that Au can covalently bond to diphenylacetylene through nitrogen or sulfur linkages while its weak interaction through oxygen linkage has non-covalent character in nature. The dependence of the molecular electronic structure of the gold–molecule complexes on the external electric field has been also studied. The electronic conduction has been analyzed from the change in the shape of molecular orbitals and the evolution of the HOMO–LUMO gap of the molecule-gold complexes under the influence of the electric filed.     

Real-time heating and power characterization of cells in standard cell designs

In today's digital electronic integrated circuits device heating is one of the most critical issues. Overheating can cause failures in functionality and device malfunction. In certain circumstances overheating of ICs can cause physical destruction of the device itself. This paper introduces a solution to determine cell and gate heating curves across the standard cell IC's surface. The presented methodology and toolset is tightly integrated into standardized logic simulator engines thus providing digital circuit designers a low-level, cell-resolution temperature distribution map during logic simulations. Actual temperatures of each consisting cell of the design can be monitored throughout the whole logic simulation. By being able to monitor temperatures of digital cells during initial simulations, it allows us to detect hot-spots and overheating caused malfunctions far before manufacture. By using the spatial location and temperature magnitude of hot-spots acquired from the presented methodology, place and route (P&R) tools can be driven to change cell placement and routing in order to avoid heating caused failures. Additionally, cooling solutions can be developed using the simulated temperature maps of the IC's surface. This paper also presents various aspects of power characterization methods which were used throughout the experiments.     

Robust decentralized PID-based power system stabilizer design using an ILMI approach

Thanks to its essential functionality and structure simplicity, proportional-integral-derivative (PID) controllers are commonly used by industrial utilities. A robust PID-based power system stabilizer (PSS) is proposed to properly function over a wide range of operating conditions. Uncertainties in plant parameters, due to variation in generation and load patterns, are expressed in the form of a polytopic model. The PID control problem is firstly reduced to a generalized static output feedback (SOF) synthesis. The derivative action is designed and implemented as a high-pass filter based on a low-pass block to reduce its sensitivity to sensor noise. The proposed design algorithm adopts a quadratic Lyapunov approach to guarantee α-decay rate for the entire polytope. A constrained structure of Lyapunov function and SOF gain matrix is considered to enforce a decentralized scheme. Setting of controller parameters is carried out via an iterative linear matrix inequality (ILMI). Simulation results, based on a benchmark model of a two-area four-machine test system, are presented to compare the proposed design to a well-tuned conventional PSS and to the standard IEEE-PSS4B stabilizer.     

一种加速器用高压电源系统设计方案

本文提出了一种加速器用高压电源系统的设计方案，主要讨论高压开关电源的设计，对于工作在高电位的电源也进行了介绍。     

三相电容式电机的绕组型式对性能的影响

三相电容式电机通过在空间互差90.电角度的主、副绕组相互作用,能有效地削弱电机的谐波磁势,提高电机的效率和功率因数.本文就生产的两台样机进行实验,测定其工作性能和起动性能,指出应通过选择合适的绕组重绕形式,才能最大限度削弱电机谐波磁势、改善电机性能.并同时提出增加电机起动转矩的方法.     

QH(R)6型熔融钢丝绳电动葫芦设计与计算

对10t熔融葫芦的设计进行了探讨,通过减小原有产品起升扭矩来提高机构工作级别,在此基础上增加安全制动器装置、多重限位装置、紧急停止开关、遥控器等部件,较详细地阐述了棘轮停止器及主要受力件的设计计算.     

Electric-field-induced self-assembled one-dimensional nanostructures in CdX and HgX (X=Se, Te) thin films

Self-assembling due to the presence of electric field during deposition in the spray deposited nanocrystalline CdX and HgX (X=Se and Te) thin films is reported. The films are deposited using solvothermally synthesized nanoparticles dispersed in 1-butanol and sprayed on the glass substrates at 200 °C without any voltage as well as by applying a voltage to the nozzle. The electron microscopy studies reveal the formation of nanorods for the films deposited with the voltage. The X-ray diffractograms of CdSe films deposited without voltage and with voltage show hexagonal crystal structure. On the other hand, CdTe films deposited without voltage show cubic crystal structure and the films deposited with voltage show hexagonal crystal structure. HgX films deposited without and with voltage show cubic crystal structure and there is no nanorod formation below 700 V. HRTEM studies show the growth direction of the CdX nanostructures. In view of the self-assembly observed under voltage, the induced dipole moment and the resultant electrostatic interaction are expected to be the driving force for the growth of nanorods. Blueshift in the band gap is observed for all the films deposited without and with voltages, and it is attributed to the quantum confinement effect due to the formation self-assembled one-dimensional nanostructures.     

Logistics cost analysis of rice straw for biomass power generation in Thailand

The logistics of the fuel supply have a large impact on the economy of a biomass power generation facility, especially for low density biomass fuels like straw. A detailed cost analysis of a typical rice straw logistics process for two baling options in three regions of Thailand shows that the costs for all logistics operations vary from a minimum of 18.75 USD/t for small rectangular bales in the Northern region of Thailand to maximum 19.89 USD/t for large rectangular bales in the North-eastern region. The difference in costs is not very significant due to the higher ownership and operating costs of the equipment for using large rectangular bales; however, the specific fuel consumption cost is substantially lower by around 17.5% and a total transport cost reduction is about 31.5%. Analysis of the logistics economies of scale for projected power plant capacities of 2-35 MW_e showed that each doubling the capacity of the energy facility increases the specific costs of the logistics operations only by around 4% in all regions.     

Power management system for a 2.5 W remote sensor powered by a sediment microbial fuel cell

One of the challenges in using wireless sensors that require high power to monitor the environment is finding a renewable power source that can produce enough power. Sediment microbial fuel cells (SMFCs) are considered an alternative renewable power source for remote monitoring, but current research on SMFCs has demonstrated that they can only produce several to tens of mW of continuous power. This limits the use of SMFCs as an alternative renewable remote power source to mW-level power. Such low power is only enough to operate a low-power sensors. However, there are many remote sensors that require higher power, on the order of watts. Current technology using a SMFC to power a remote sensor requiring watts-level intermittent power is limited because of limitations of power management technology. Our goal was to develop a power management system (PMS) that enables a SMFC to operate a remote sensor consuming 2.5 W of power. We designed a custom PMS to store microbial energy in capacitors and use the stored energy in short bursts. Our results demonstrate that SMFCs can be a viable alternative renewable power source for remote sensors requiring high power.     

Modelling of Functionally Graded Adhesive Joints

Nowadays, there is a strong trend towards the use of functionally graded materials, with particular importance for the functionally graded joints. The main objective of this work was to study a functionally modified adhesive in order to have mechanical properties that vary gradually along the overlap of a joint, allowing a uniform stress distribution along the overlap. This allows for a stronger and more efficient adhesive joint and would permit to work with much smaller areas, reducing considerably the weight of the structure which is a key factor in the transport industry. In the proposed joint, the adhesive stiffness varies along the overlap, being maximum in the middle and minimum at the ends of the overlap. The functionally graded joint was found to have a higher joint strength compared to the cases where the adhesive has homogeneous properties along the overlap. A simple analytical model to study the performance of the functionally graded joints was developed. The differential equation of this model was solved by a power series. Numerical modelling by finite element analysis was performed to validate the analytical model developed.