A high-performance switch fabric for integrated circuit and packet switching

This paper describes an architecture for a high-performance switching fabric that can accommodate circuit-switched and packet-switched traffic in a unified manner. The switch fabric is self-routeing and uses fixed-length minipackets within the switching fabric for all types of connections. Its kernel architecture is based on a routeing topology with individual connection paths from all inputs to all outputs and with FIFO queuing at each output. Owing to the disjoint connection paths, there is no internal blocking, and because of output queueing, output port blocking is prevented to a great extent. The uniformity in architecture allows construction of any size fabric from a single basic module which could be realized on a single chip. Larger-size configurations can be realized either as single-stage or multistage configuration. The second part of this paper discusses performance aspects and gives results and dimensioning guidelines for both circuit-switched and packet-switched traffic.     

Deformation behaviour and mechanical properties of polypropylene processed by equal channel angular extrusion: Effects of back-pressure and extrusion velocity

Severe plastic deformation by equal channel angular extrusion (ECAE) is an ingenious deformation process used to modify texture and microstructure without reducing sample cross-section. The application of single ECAE pass to polypropylene (PP) was meticulously investigated at room temperature using a 90° die-angle tooling. The ECAE-induced deformation behaviour was examined in relation to the load versus ram-displacement curves. Depending on extrusion conditions, PP displayed various types of plastic flow. For ram velocities beyond 4.5 mm/min, severe shear bands consisting of successive translucent and opaque bands were observed, accompanied on the top surface by more or less pronounced periodic waves. Although the application of a back-pressure significantly reduced the wave and shear-banding phenomena, slightly inhomogeneous shear deformation was still observed. Shear bands were only suppressed by decreasing extrusion velocity. The strain-induced crystalline microstructure was investigated by X-ray scattering. Shear-banded samples exhibited a strong texturing of the (hk0) planes along the shear direction in the translucent bands whereas perfect crystalline isotropy appeared in the opaque bands. Application of back-pressure and/or reducing ram velocity resulted in uniform texturing along the extruded sample. Yet, texturing changed from single shear to twin-like shear orientation about the shear direction. Mechanical properties changes of the extruded samples due to back-pressure and extrusion velocity effects were analyzed via uniaxial tensile tests. The tensile samples displayed multiple strain localizations in shear-banded materials whereas quite homogeneous deformation appeared for non-banded ones. These effects were connected with the crystalline texturing. The results also revealed significant increase in the strain hardening after ECAE. Digital image correlation technique suitable for large deformation was used for determining the full-field strain of the tensile samples in relation to tensile strain and ECAE conditions.     

节流调速动态刚度分析

论述和分析了三种液压节流调速方法问题，从而得到这三种回路速度的动态刚性特性。三种调速回路在刚性影响下的应用场合。     

Processing of a magnesium alloy by equal-channel angular pressing using a back-pressure

Experiments were conducted on the magnesium AZ31 alloy to evaluate the significance of conducting equal-channel angular pressing (ECAP) with a back-pressure. Following processing by ECAP, the values of the Vickers microhardness were recorded on the cross-sectional planes and microstructural observations were undertaken using transmission electron microscopy. The results show an increase in the hardness in the first pass with significant microstructural inhomogeneity and a transition towards a more homogeneous structure with subsequent passes. The grain size was measured as 0.9 μm after 8 passes. A comparison with published data on the same alloy processed by ECAP without a back-pressure suggests several advantages in incorporating a back-pressure into ECAP. These advantages include the ability to achieve greater grain refinement, a potential for pressing at lower temperatures and the development of a more rapid evolution towards a homogeneous microstructure.     

环境因素对直接空冷机组的影响

直接空冷机组的运行状况受周围环境的影响很大,不同的风速、风向不仅会影响到机组运行的经济性,甚至还会造成掉闸停机事故。本文在总结火力发电厂空冷系统特点的基础上,对现场环境及所采集数据进行了系统分析,重点研究了环境作用对直接空冷机组空冷风机吸入风量和入口温度以及空冷机组背压影响,同时分析了环境温度的变化对空冷机组供电煤耗的影响。     

小型热电站背压式汽轮机的选型

本文就小型热电站背压式汽轮机的选型问题进行了论述,对汽轮机额定功率,初参数、终参数的选择提出了自己的看法,特别是对热化系数α的确定提出了见解。     

Buffer allocation for real-time streaming applications running on heterogeneous multi-processors without back-pressure

The goal of buffer allocation for real-time streaming applications is to minimize total memory consumption, while reserving sufficient space for each data production, without overwriting any live data and guaranteeing the satisfaction of real-time constraints. Previous research has mostly focused on buffer allocation for systems with back-pressure. This paper addresses the problem of buffer allocation for systems without back-pressure. Since systems without back-pressure lack blocking behavior at the side of the producer, buffer allocation requires both best- and worst-case timing analysis.Our contributions are (1) extension of the available dataflow techniques with best-case analysis; (2) the closest common dominator-based and closest common predecessor-based lifetime analysis techniques; (3) techniques to model the initialization behavior and enable token reuse.Our benchmark set includes an MP3 decoder, a WLAN receiver, an LTE receiver and an LTE-Advanced receiver. We consider two key features of LTE-Advanced: (1) carrier aggregation and (2) EPDCCH processing. Through our experiments, we demonstrate that our techniques are effective in handling the complexities of real-world applications. For the LTE-Advanced receiver case study, our techniques enable us to compare buffer allocation required for different scheduling policies with effective impact on architectural decisions. A key insight in this comparison is that our improved techniques show a different scheduling policy to be superior in terms of buffer sizes compared to our previous technique. This dramatically changes the trade-off among different scheduling policies for LTE-Advanced receiver.     

StarSync: An extendable standard-cell mesochronous synchronizer

StarSync, a mesochronous synchronizer, enables low latency and full throughput crossing of clock domain boundaries having same frequency but different phases. Full back pressure is supported, where the receiver can start and stop accepting words without any data loss. Variable depth buffering is provided, supporting a wide range of short and long range communications and accommodating multi-cycle wire delays. Burst data can also be accommodated thanks to buffering. Dynamic phase shifting due to varying voltage and temperature are mitigated by increasing the separation between write and read pointers. The synchronizer is exposed to metastability risk only during reset. It is suitable for implementation using standard cell design and requires neither delay lines nor other full custom circuits. It is shown that a minimum of four buffer stages are required, to mitigate skew in reset synchronization, in contrast with previous proposals for three stages.     

Research on back- pressure compensation characteristics of a pilot-assisted load control valve applied in overrunning load hydraulic systems

This paper reports the research of proportion flow control with back-pressure compensation feature on an LCV (load control valve). The back-pressure compensation feature means when back-pressure rises, flow of the LCV can be unchanged or lower. The back-pressure compensation feature is very important to the safety of the system, because high back-pressure will make the main valve open larger and lowering speed be undesired faster. In this paper, static equilibrium equations of LCV were established and influence relationship of back-pressure and other parameters was derived. In addition, back-pressure influence was simulated, based on above analysis a preliminary optimization scheme was proposed and tested. After that, the method of back-pressure compensation was proposed and has been verified by simulation. Finally, an LCV with back-pressure compensation feature was tested on the test rig. Experiment data validates that the main flow of the LCV with back-pressure compensation method was lower under a higher back-pressure and the pilot pressure control region was unchanged.     

背压式硅压阻压差传感器的研制

根据伺服系统高精度、高可靠性的测量需求,研制一种背压式硅压阻压差传感器.传感器基于硅的压阻效应,与目前硅压阻压差传感器使用薄膜隔离式敏感芯体不同,其感压芯片的背部直接接触被测介质感受压力,避免了硅油介质传递压力.因此,敏感芯体结构简单可靠,提高了传感器长期承压的可靠性.介绍背压式硅压阻压差传感器的原理及设计与实现,主要包括芯体设计、电路设计、结构设计等.传感器通过性能试验以及环境适应性试验的考核,并在伺服系统上进行相关试验,结果证明能够满足伺服系统使用要求.