Feeding path and movable die designs are crucial to implement bellows manufacturing with an appropriate hydraulic pressure and make the products satisfy the required geometrical and dimensional specifications. In this paper, a tube hydroforming process combined with movable die designs is developed to obtain an appropriate forming range of the internal pressure and increase the thickness uniformity in the formed product. Two kinds of feeding types are proposed to discuss the effects of the feeding path and die design on the convolution heights and thickness uniformity in the formed bellows. A finite element simulation software “DEFORM” is used to analyze the plastic deformation of the tube within the die cavity using the proposed feeding types for three different shape bellows. Allowable forming ranges of internal pressures for sound products with required tolerances in geometry and dimensions using different feeding types are also investigated. Finally, tube hydroforming experiments of three-convolution bellows are conducted and experimental thickness distributions and convolution heights of the products are compared with the simulation results to validate the analytical modeling with the proposed movable die concept.

To mitigate the impact of distribution system service quality due to high penetration of PV systems, a Distribution Renewable Energy Advanced Management System (DREAMS) is developed and installed at Feng Shan District of Taiwan Power Company (Taipower). The PV gateways and the public 4G communication system are applied to monitor the power generation and the voltage of 24 PV systems and to report the operation data to the master station. The power factor for the PV smart inverter is adjusted automatically to absorb the reactive power when the overvoltage problem occurs. When the distribution automation system (DAS) performs the functions of noninterruptible load transfer and service restoration after fault contingency, the DREAMS executes the power factor control for the PV smart inverters before the line switches are operated. The coordination control of DAS and DREAMS can prevent the overvoltage problem for a distribution system during the process of load transfer between distribution feeders with high PV penetration.

In order to overcome the key escrow problem, Al- Riyami and Paterson introduced the concept of certificateless public key cryptography (CL-PKC) in 2003. CL-PKC requires neither public key certification nor the key escrow problem. After that, CL-PKC has been widely applied. In 1991, Girault defined three security levels of the key generation center (KGC), where the higher level of KGC means the stronger security of the system. Recently, lots of certificateless signature schemes and their security models have been presented. However, there is no certificateless signature scheme proposed in the literature that achieves the property of Girault's level-3 security without random oracles. In view of aforementioned issues, we propose a new construction of certificateless signature scheme. The proposed certificateless signature scheme is provably secure in the standard model and satisfies Girault's level-3 security. The security of the proposed scheme is based on the hardness of generalized computational Diffie-Hellman and many Diffie-Hellman problems.

This paper presents a novel frequency-offset technique to enhance operating range of frequency synthesizers for long-term evolution-advanced and cognitive-radio applications. Conventional wideband frequency synthesizers typically have complex architectures, such as multiple phase-locked loops (PLLs), multiple voltage-controlled oscillators, and multiple mixers, to increase operating range. These complex architectures have high cost and power consumption. In this study, the proposed technique substantially increases the operating range of the frequency synthesizer by using only a single PLL to simultaneously lock two mixing oscillators. The presented frequency synthesizer is implemented using 0.18-mu m CMOS technology. Performance tests demonstrate that the frequency synthesizer achieves a very wide operating frequency range from 50 MHz to 4.8 GHz with a phase noise lower than -100 dBc/Hz at a frequency offset of 100 kHz. The period of stability for a switching frequency of 40 MHz is shorter than 40 mu s.

The GI (graded-index) POFs (Plastic optical fibers), which has been proven to reach distances as long as 1 km at 1.25 Gb/s has a relatively low numerical aperture . Therefore, the efficient coupling of GI POFs to the light source has become critical to the power budget in the system. Efficient coupling for a POFs system normally involves either a separate lens or the direct formation of the lens at the end of the fiber. Forming the lens-like structure directly on the fiber end is preferred for simplicity of fabrication and packaging, such as polishing and fusion, combine different fibers with the cascaded fiber method and hydroflouride (HF) chemical etching. These approaches are well established, but applicable only to glass. Optical assembly architecture for multichannel fibers and optical devices is critical to optical fiber interconnections. Multichannel fiber-pigtail laser diode (LD) modules have potential for supporting higher data throughput and longer transmission distances. However, to be of practical use, these modules must be more precise. This work proposes and manufactures lensed plastic optical fibers (LPOF) array. This novel manipulation can be utilized to fabricate an aspherical lens on a fiber array after the UV curing of the photo-sensitive polymer; the coupling efficiency (CE) is increased and exceeds 47% between the LD array and the fiber array.

is paper presents an optimal capacitor planning strategy by considering the reactive load duration curves of distribution feeders to reduce system power loss and enhance reactive power compensation in Taipower. The objective function is formulated by including feeder peak power loss, nual energy loss and investment cost of capacitors with discrete capacities. In the proposed method, the immune algorithm (IA) is applied to lye the optimization problem and to derive the optimal sizes and locations of capacitors to be installed along the feeders by representing the objective function and constraints as antigens. The affinity calculation is embedded in the solution process to guarantee the diversity and prevent stagnation of local sub-optimality. After performing the genetic evolution, an antibody which fits the antigen best is determined to be the optimal capacitor planning. The three-phase load How analysis is executed by considering time-varying load characteristic of customers to solve stern power loss on annual basis with various capacitor-planning scenarios. The marginal cost benefit (MCB) of the reactive power compensation applied to solve the timings for the switched-type capacitors. A practical distribution feeder is selected for computer simulation to demonstrate the effectiveness of the proposed IA methodology to solve the capacitor planning by evaluating the yearly peak power loss and total energy loss er the life cycle of capacitor investment. Copyright (C) 2010 John Wiley & Sons, Ltd.

The practice of transformer load management (TLM) in Taipower to determine the daily power pro. le and the peak loading of distribution transformers by integration of customer information systems (CISs) such as, automated mapping/facilities management/geographic information system and load survey system is presented. The load survey study is conducted by selecting 672 customers for installation of digital power meters to measure the customer power consumption within 15 min intervals. The typical load patterns of low-voltage residential, commercial and industrial customer classes are derived by executing statistic analysis of power consumption of test customers. A narrow-band power line carrier-based identifier is developed to identify all of the customers served by each distribution transformer. The hourly power consumption of each customer is determined by allocating the monthly energy consumption according to the typical load pattern of the corresponding customer class. The peak loading of each distribution transformer is then estimated by integrating the power consumption of all customers served. The overloading flags and peak loading levels of all transformers are then displayed on the digital mapping system. The TLM program proposed in this study has effectively assisted Taipower distribution engineers to identify the potentially overloading transformers for load reduction to mitigate the transformer damage during the hot summer season.

In this paper, a narrow-band power line carrier (PLC) based identifier has been designed and developed to support the on line identification of customers served by each distribution transformer. To investigate the transmission characteristics of power line carrier signal over low voltage distribution lines, the mathematical model of distribution components such as transformers, low voltage conductors, customer appliances, etc. at PLC carrier frequency are derived and included in the computer simulation. The two port network is used to represent the low voltage distribution systems and Matlab/Simulink is applied for the analysis of PLC signal attenuation from the secondary side of transformer to the customer locations. After completing the development of PLC based identifier, the field test of a commercial building has been executed. The PLC signal strength and the noise level have been measured to verify the effectiveness of the identifier to determine the connectivity of distribution transformer and the customers served without requiring power service interruption.

This paper presents the power quality assessment of a hot strip mill with cycloconverters for an integrated steel- making facility. Due to the stochastic operation characteristics of cycloconverters, the electric power consumed by the hot strip mill fluctuates dramatically with the harmonic currents of different integer orders and non-integer orders. Both of the harmonic distortion and voltage flicker problems have been introduced to deteriorate the power quality of the industrial customer. To mitigate the harmonic pollution and provide proper reactive power compensation at the same time, two single-tuned and three high-pass passive filters have been therefore applied according to the harmonic load flow analysis. After removing the resistor due to flash over damage, the 6.8 th order high-pass filter has been converted to be a single-tuned filter. The impact of harmonic distortion on the existing filters and other equipments is investigated in this paper to ensure the harmonic distortion of the hot strip mill to be within the tolerance limit with the new configuration. To represent the harmonic current injection more accurately for the harmonic load flow analysis, the harmonic currents generated by cycloconverters are determined by field measurement. It is found that the total voltage harmonic distortion THD v solved by computer simulation is very close to the actual harmonic distortion. According to the harmonic load flow analysis, the serious harmonic pollution problem introduced by the cycloconverter drive system can be mitigated effectively by the implementation of proposed harmonic filter banks. Besides, the voltage flicker problem due to dramatic variation of large reactive power consumption of the hot strip mill can be solved by proper control of cycloconverters.

The stochastic harmonic distortion of a mass rapid transit (MRT) system is investigated by considering the dynamic load behaviour of train sets. A mathematical model of 12-pulse uncontrolled rectifiers without interphase transformers is derived and applied to the harmonic load flow analysis to workout the power demand and the harmonic injection currents at traction substations for each time snapshot. According to the mean values and standard deviation of harmonic currents, the stochastic harmonic load flow analysis is performed to find the average and the confidence interval of harmonic voltage distortion for all system buses. A comparison with the conventional harmonic load flow analysis, which considers only the average load demand and the mean harmonic injection current, reveals that the method proposed can evaluate the voltage harmonic distortion of the system more accurately to provide better guidance for the strategy of harmonic mitigation.

This paper proposes a novel methodology to estimate the impact of temperature rise to the system power consumption. The load survey study is performed to derive the typical load patterns of the residential, commercial, and industrial customer respectively. By analyzing the relationship of customer power consumption and temperature, the temperature sensitivity of power consumption for each customer class is determined. By integrating the typical load patterns and total energy consumption, the daily power profile's and load composition of Taipower system has been obtained. With the load compositions and temperature sensitivities of all customer classes, the hourly increase of system power loading due to temperature rise is solved. According to the study, the peak loading of Taipower system will be increased by 585 MW or 2.4% of the system power demand for each 1 degreesC temperature rise. The actual Taipower system loading is used to verify the accuracy of the temperature sensitivity solved by the proposed method. It is concluded that the power increase due to temperature rise has been mainly contributed by the usage of air conditioners in the commercial and residential customers.

This paper is to investigate the optimal switching problem of distribution systems by considering the customer load characteristics and the effect of temperature change to the customer loading. The load survey is applied to derive the typical load patterns of residential, commercial, and industrial customer classes. The power consumption of sample test customers and weather information are used to solve the hourly temperature sensitivity of power consumption for each customer class. All the customers served by each distribution transformer are identified and their monthly energy consumption is retrieved from the customer information system in Taipower. The hourly loading of each service zone and its change due to temperature rise are obtained based on the customer load consumption and its temperature sensitivity. By performing the connectivity trace to find the feeder configuration and executing the three-phase load flow analysis, the hourly current loading of line switches, distribution feeders, and main transformers in substations are solved. The binary integer programming is then applied to determine the temperature adaptive optimal switching operation for noninterruptible load transfer among distribution feeders and main transformers.

The effect of PbSn solder joint strength on temperature tests in laser diode packaging has been studied experimentally and numerically. It was found that the solder joint strength increased as temperature cycle number increased. A finite-element method (FEM) analysis is performed on the calculation of joint strength of PbSn solder in temperature cycling tests for laser diode packaging. Numerical calculations were in good agreement with the experimental measurements that the solder joint strength increased as the temperature cycle increased. This is may be due to the redistribution of the residual stresses within the solder during the temperature cycling tests, and hence reducing the residual stresses and increasing the solder joint strength as the temperature cycle number increased. The result suggests that the FEM is an effective method for predicting the solder joint strength in laser diode packages.

This paper investigates the load transfer function of the distribution automation project to be implemented in Taipower distribution system. During the summer peak season, the main transformers of distribution substations in Taipower become overloaded due to the usage of air conditioners in the commercial and residential sections. The noninterruptible load transfer among distribution main transformers has to be executed for power reallocation to solve the problem. In this paper, the hourly loading of each service zone in the distribution system is determined by the load composition of the customers served within the service zone. The hourly current flows of line switches are derived by simplified three-phase load flow analysis. Applying the binary integer programming (BIP) to solve the distribution system reconfiguration so that the load transfer among main transformers can be obtained derives the optimal switching operation. With the execution of the load transfer for Taipower distribution system by the proposed BIP method, the load balance among distribution main transformers during the summer peak hours is obtained. A Taipower distribution system with six feeders is selected for computer simulation to demonstrate the effectiveness of the proposed methodology.

This paper illustrates the load survey project which has been designed and implemented in Taipower since 1993. The multiple functions of power system planning and operation to be supported by the load survey system have been identified to justify the cost effectiveness of the project. The stratified sampling algorithm has been applied to determine the proper size of customers for the installation of intelligent meters so that the customer load profiles solved can represent the actual system load characteristics in a sufficiently confidential level. In the study, the test customers within each customer class are selected by the random number method based on the standard deviation of power consumption of all customers in the class. The power consumption of test customers within every 15 minutes has been collected for 4 years and the statistic analysis has been applied to derive the typical load patterns of each customer class. With the precious information provided by the load survey system, Taipower is considering to revise the load forecasting and system planning, to design more proper tariff structure according to the actual contribution of power consumption by each customer class and the corresponding electricity service cost. By investigating the load composition of each customer class, more effective load management strategies are also designed by Taipower to reduce the system load demand during summer peak period

Raman scattering has been used as a technique for characterization of the sputtered IrO2 thin films (SIROF) deposited on different substrates under various conditions. Compared with the spectrum of single crystal IrO2, red shift and broadening of the linewidth of the Raman peaks of SIROF are observed. X-ray diffraction measurements of SIROF were also carried out to assist the identification of the factor that influences the linewidth broadening of the Raman features. The results indicate that amorphous–crystalline transition for IrO2 phase can be achieved at substrate temperature of 200–300 °C. The line-shape and position of the Raman features vary for films deposited on different substrates under the same conditions. These differences can be due to the existence of stress between IrO2 and the substrates.

This paper develops the coordination of a load-shedding scheme for a large industrial customer with several cogenerator units, A detailed description of each design procedure is included. The loads are tripped by the underfrequency relays, to prevent the power system from collapse when the plant becomes isolated, due to a utility service outage. Different system fault cases have been selected to derive the proper formulation of a load-shedding scheme, according to the historical operation records, The key factors, such as frequency settings, number of load-shedding steps, size and location of the loads to be tripped, relay time delay, and the coordination with the generator protection scheme, were examined through the simulation of the transient stability program, The proper load-shedding scheme has been designed, and the related hardware has been installed in the plant, to keep the system from blackout when the disturbance occurs.

This paper proposes a load survey system to determine the load characteristics of various customer classes in an electric utility company. The questionnaires are adopted to find the power consumption of key electric appliances. The actual power consumption of hundreds of customers are collected by intelligent meters. Sampling theory has been applied to find the proper sample size of both questionnaires and field tests so that the customer load characteristics will be derived with sufficient confidence level. Statistical analysis is then performed to find the power consumption model of each customer class based on the power measurement of field tests. The temperature effect on the power consumption of each customer class is also investigated by differentiating the proposed power consumption model with respect to the ambient temperature. The proposed method has been adopted by the Taipower company to better understand the customer load characteristics to support various functions of power system planning and operation in a more effective manner.

The substation loading is highly correlated with the customers served. The substations in a distribution system can be categorized as residential, commercial and industrial. Each type has a different power consumption pattern. The substation loading will be varied according to the combination of the above three types of customers. In this paper, a supervisory functional artificial neural network (ANN) technique is applied to solve the load forecasting of three Taipower substations which serve the different customer types. The load forecasting accuracy is enhanced by considering the temperature effect on the substation load demand. With the converged ANN models derived by a training procedure, the temperature sensitivity of the substation load demand is easily obtained by the recall process. It is suggested that the substation load forecasting can be performed efficiently by the proposed method to support distribution operation effectively.