Papers by Keyword: High Speed

Abstract: With the development of digital very large scale integrated circuits (VLSI), how to reduce the power dissipation and improve the operation speed are two aspects among the most concerned fields. Based on sense amplifier technology and bulk-controlled technique, this paper proposes a bulk-controlled sense-amplifier D flip-flop (BCSADFF). Firstly, this flip-flop can change the threshold voltage of the NMOS by inputting control signals from the substrate so as to control the operating current. Secondly, the traditional RS flip-flop composed of two NAND gates is improved to a couple of inverters based on pseudo-PMOS dynamic technology. Therefore, the proposed BCSADFF can both effectively reduce the power dissipation and improve the circuit speed. Thirdly, the designed BCSADFF can work normally with ultra-dynamic voltage scaling from 1.8 V to 0.6V for SMIC 0.18-um standard CMOS process. Lastly, the Hspice simulation result shows that, compared with the traditional sense-amplifier D flip-flop (SADFF), the power dissipation of the BCSADFF is significantly reduced under the same operating conditions. When the power supply voltage is 0.9V, the power dissipation and delay of the SADFF is 6.54uW and 0.386ns while that of the proposed BCSADFF is 2.09uW and 0.237ns.

Abstract: This paper aims to develop a new systematic analysis model to predict the contact angle of ball screw in high-speed condition. In order to investigate the contact angle between the ball and raceway, a proper mechanics model of ball screw should be established. Then, considering the influence of centrifugal force at high speed, the change of contact angle will be analyzed and solved. Finally, the different factors on the influence of contact angle in different locations are analyzed. This study provides the theory basis of studying kinematics of ball screw in high speed.

Abstract: By studying the advantages and disadvantages of the conventional automatic linear door systems, it was found that flat permanent magnet linear synchronous motors (PMSLM) can satisfy high-speed long-stroke heavy-load door systems better than other techniques. In order to reach a long lifespan, the authors compared five possible topologies with flat PMLSM, and then designed a kind of magnetically suspended door system driven by a single-sided flat PMLSM and suspended by the normal force of the motor. The results demonstrate that the prototype door system satisfies the requirements.

Abstract: With respect to the application of high-speed, high-resolution A/D converter, the design and implementation of a CMOS input buffer is introduced. The buffer features high-speed and high-linearity. Its performances have been verified in a 14-bit 250MSPS pipelined A/D converter which is developed in 0.18um CMOS-based process technology. The simulation shows that the SFDR of the buffer is up to 104dB at an input clock of 250MHz with an input signal of 25MHz.

Abstract: The local distribution of the convection heat transfer coefficient (CHTC) of grinding fluids along the wheel-work contact zone under high speed grinding conditions has been investigated. A new approach has been proposed to derive the distribution of CHTCs along the contact zone by using the measured grinding temperatures and linking the distribution of local heat flux and heat partitioning to the workpiece, wheel and grinding chips. It has been found that the worktable speed is the key factor affecting the pattern of CHTC distribution, whilst the grinding speed strongly affects the overall magnitudes of the CHTCs. Down grinding mode is beneficial for achieving effective cooling under creep-feed conditions. The distribution of CHTC under faster worktable speeds shows a rather different pattern, which has to be considered when selecting the grinding mode and grinding fluid supply strategy.Keywords: Grinding, Fluid, Convective heat transfer coefficients, Temperature, High speed

Abstract: It is well known that Incremental Sheet Forming has two main drawbacks, i.e. accuracy and slowness. The former has been studied and partially solved by several researchers while the latter did not receive convincing answers. Thus, the idea of several research groups is that the process applicability is suggested only for rapid manufacturing or small batch production. The lack of knowledge is certainly caused by the available machines, like milling or Amino, which are typically used for incremental forming operations. In the present research the attention was focalized on the above limit: an experimental campaign was performed in order to evaluate the process feasibility at very high speed. To do that a lathe machine has been used instead of the conventional milling one, increasing the process speed up to two order of magnitude. An aluminum alloy, widely used in the mechanical fields, has been chosen as sample material and an experimental investigation has been aimed at determining the influence of tool speed on the material behavior.

Abstract: The tribological properties of TiN coating were studied at the speed of 40m/min-120m/min, under the load of 5N-15N at elevated temperatures between 200°C-600°C. It can be concluded that when the temperature is lower than 400°C, the coefficient of friction increased with temperature, but the value decreased because of the friction oxidation at 600°C.The wear mass loss of the coating increased with increasing of speeds and loads, and this proved the TiN coating was not adaptable to high temperature environment. The wear mechanisms of TiN coating at elevated temperature were abrasive wear, plastic deformation, oxidation wear and adhesion wear.

Abstract: Space optical communication has become a promising application as a real-time and high-speed data rate in the near future. In this paper consider into account the cut off frequency of the photodetector in the space optical communication. We analyze an appropriate quantum dot infrared photodetector for high speed response. The analysis shows PN junction structure photodiode with the wide as d in the absorption window should be designed carefully to achieve both high sensitivity and high speed.