Advanced Materials Research Vol. 660

Abstract: A dual-mode low pass sigma-delta (ΣΔ) modulator at clock rates of 160 and 100 MHz respectively with cascaded integrators is presented for WCDMA and Bluetooth applications. One of main features is that cascaded integrators with feedback as well as distributed input coupling (CIFB) topology erase a summation amplifier and save power consumption. Another feature is that only one set loop filter is designed by switching capacitors to achieve a dual-mode function and greatly saves chip area. A prototype is fabricated in TSMC 0.18-m CMOS process. At the supply voltage of 1.8 V, measured results have achieved the SNDR of 42/33 dB over 1/2 MHz, respectively for Bluetooth/WCDMA. The chip dissipates a low power of 10.5 mW. Including pads the chip area is only 0.61 (0.71× 0.86) mm².

Abstract: In this paper, a low power dissipation divide-by-two frequency divider is presented. The master latch and the slave latch of the divide-by-two frequency divider are stacked in cascode to reuse the current. The frequency divider can operate with only half the current of a conventional divider. A divide-by-two frequency divider based on the proposed topology is designed and simulated in a 0.18μm 1P6M CMOS process. Simulation results show the frequency divider can operate up to 11GHz with only 0.66mW power dissipation under 1.8V supply voltage. And it also demonstrates good phase noise performance.

Abstract: For wireless sensor networks, energy efficiency is one of the most important subjects in recent research. In this paper, an energy-efficient multi-hop scheme based on cooperative MIMO (multiple-input multiple-output) technique is proposed for wireless sensor networks. Different from other papers, we consider a single cluster transmission scenario in which energy consumption is optimized by selecting the hop length and modulation constellation size. The optimal energy consumption formula is derived and proved mathematically. In addition, the minimum energy consumption per bit is calculated numerically.

Abstract: In this paper, we derive a theoretical model for the higher order FWM power in WDM networks with NZDSF fibers for the first time. We have investigated the higher order FWM power theoretically and by numerical simulations. Dividing the fiber into finite number of elements and applying the boundary conditions, allow us derive an expression for second order power penalty. At the end of each element we derive the first order FWM power for all wavelengths and use these values to calculate the second order FWM power in the next element. Consequently, for each channel we can compute the total second order FWM power penalty at the end of the fiber.

Abstract: A new numerical control (NC) rotary table with high accuracy is presented. Time grating, which was taken as the angle measuring unit, was installed inside the rotary table to measure the angular displacement in real time. Moreover, the signal of time grating was used as the feedback to realize full-closed loop control for improving the control accuracy of the NC table. Furthermore, the problem of insufficient subdivision of the step angle of the stepping motor could be solved by increasing the transmission ratio of motor shaft and rotary table. Experiments prove that the NC rotary table has the advantages of high control accuracy and running steadily, and the NC system shows a good application prospect in the field of machining.

Abstract: Energy management strategy is important to keep microgrid stable. In this paper, energy management strategy of Wind-PV-ES hybrid microgrid is proposed. Due to the power output of wind and PV are unknown quantities, the key point of Wind-PV-ES hybrid energy management lies in the energy management of storage battery. The flow charts of energy management strategy are given in detail and Wind-PV-ES microgrid model is built with DigSILENT/PowerFactory. Then the transition state simulation as to the micro-grid mode switching process is carried out. The result shows that the proposed energy management strategy could keep connected bus voltage and micro-grid frequency stable in grid-connected mode, islanding mode and during micro-grid mode switching.

Abstract: Since many works have been devoted to attack the Block Cipher, in this paper, on the base of the prior work, we take the advantage of the capacity of parallel computing of GPU and use Light Encryption Device (LED) as an object of experiment. After modifying the algorithm, we reduce the time complexity of the attack that reveals the whole key of LED from 218 to 210.

Abstract: SSLVPN is widely used in Web applications, e-commerce, teleworking, etc...Due to the need to provide security, the complex computing has been seriously upset the performance of SSLVPN, may even cause the VPN throughput rates decline by one to two orders of magnitude. To improve SSLVPN encryption performance, domestic and foreign scholars have made a number of studies. This paper focuses on the SSLVPN with hardware acceleration devices, and put forward a packet-combining algorithms，which could effectively improve encryption performance and data throughput of SSLVPN.

Abstract: The rise in energy costs urged the need in minimizing the energy consumption. As significant amount of energy is used for illuminating in educational buildings such as lecture halls and lecture rooms, improvements is needed to avoid energy waste for unoccupied and daylight hour. The lighting will be controlled based on demand to save the energy costs. This paper proposes a concept of smart energy saving classroom system using programmable logic controller (PLC). It integrates the lighting and air conditioner control system. The system is tested in one lecture room in Universiti Teknologi Petronas (UTP), Malaysia. Software for this project includes Simatic Manager, Wincc Flexible and Microsoft Visio 2010.The hardware includes Siemens S300 series PLC, Siemens 10 inch touch screen, network cable and MPI cable. The inputs are sensor at the door and sensors at each of the student seat while the outputs are the projector dc motor, lights, air-conditioner and touch screen. The proposed system offers a costs-saving solution with low maintenance and gives great performance results.

Abstract: The Computer Generated Hologram（CGH）technique is the main method for optical testing the free form surface .For testing a convex free form surface mirror, a CGH element with the surface testing, interferometer and free form mirror precise position function was designed by use of appropriative software, the testing precision was less than 0.011λ（λ=632.8nm）in RMS value by this means.