Time-domain Analysis of Laboratory Experiments on the Transient Pressure Damping in a Leaky Polymeric Pipe

Water Resources Management - The pressure damping occurring in pressurized pipes with a leak during transients has been examined as a diagnostic tool – the so-called transient damping method...     

Monolithic V-band frequency converter chip set development using0.2 μm AlGaAs/InGaAs/GaAs pseudomorphic HEMT technology

Monolithic approaches of the development to V-band frequency converters have the advantages of lighter weight and lower cost over conventional hybrid approaches for high volume insertions into satellite communication systems. This paper presents the design, fabrication, and performance of a monolithic V-band frequency converter chip set using 0.2 μm AlGaAs/InGaAs/GaAs pseudomorphic HEMT technology. This chip set consists of three monolithic macrocells and a microcell: an upconverter, a downconverter, and a frequency multiplier for LO signal. A monolithic balanced amplifier microcell is also used to form the LO chain. Individual components, including amplifiers, mixer, and frequency doublers are also described. The superb measured results obtained from this chip set show great promise of the MMIC insertions for the system applications, and represent state-of-the-art performance of MMIC at this frequency     

Experimental Evidence of Hysteresis in the Head-Discharge Relationship for a Leak in a Polyethylene Pipe

The relationship between leak outflow from a damaged pipe and flow condition inside the pipe plays a crucial role in pressurized pipe systems management. As an example, this relationship is used in leakage reduction techniques based on pressure control and in leak detection techniques based on inverse analysis. To explore the relationship between total head inside the pipe and leak outflow for a single leak in a polyethylene pipe, tests were carried out at the Water Engineering Laboratory of the University of Perugia. These tests point out that the viscoelastic nature of the pipe material gives rise to a hysteretic behavior of the investigated relationship, i.e., the outflow depends not only on the synchronous total head but also on the total head time history and variation rate.     

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<正>随着印刷质量接近胶印的彩色高速喷墨印刷技术的出现,印刷企业和数据中心开始尽力证明是否应该将这项新技术投入到实际生产中去。企业是否应将现有技术升级为高速喷墨技术的决策会受到多种因素影响,这一决策的投资回报率也尚不明确。与以前相比,企业若采用喷墨技术意味要使用全新的思考方式,这就需要你在实现系统功能的同时对现有的运行和操作方式做出相应的改变。在中小型印刷企业中,这个决策将会对生产系统中的各个方面产生影响,包括你的目标市场,以及你该如何对产品本身、产品生产流程、质量、材料、仓     

Leak Size,Detectability and Test Conditions in Pressurized Pipe Systems

The relationships between leak geometry and detectability are explored with a distinction between steady- and unsteady-state based techniques. Various criteria to evaluate the size and detectability of a leak are first discussed. These criteria can be useful for the benchmarking and the comparison of different techniques. Since the test conditions play a crucial rule in leak detectability, the proposed criteria take this effect into account. Furthermore, they show that while in steady-state conditions increases in system pressure enhance leak detectability, in transient state, by contrast, higher pressures tend to decrease detectability. This effect is also confirmed by experimental tests carried out at the Water Engineering Laboratory of the University of Perugia.     

In-Line Pipe Device Checking by Short-Period Analysis of Transient Tests

In this paper, the results of laboratory transient tests concerning the interaction between a pressure wave and an in-line device are discussed. Transients are generated by means of a fast and complete closing of an end valve, and pressure measurements are carried out just upstream of the maneuver valve. The main effect of the device on the pressure time-history—hereafter referred to as pressure signal—is a sharp increase caused by the pressure wave reflection. Three experimental setups are considered, in which different in-line devices are installed (i.e., a ball valve, a butterfly valve, and different-sized orifices). The pressure signal is analyzed in the time domain, and a reliable evaluation of the device location is obtained by means of wavelet functions. Furthermore, on the basis of the value of the pressure increase, the status of the device can be determined; experimental results are synthesized in a dimensionless diagram. Finally, criteria for using the obtained results in other pipe systems are discussed.