泥沙处理自动调压脉冲喷水器设计与应用

黄河下游水文测站多年来在泥沙处理工作过程中,一直采用房顶挂吊水桶的方法解决泥沙处理过程冲刷沙桶内泥沙用水的问题。在实际操作过程中存在很多缺点,为解决上述问题,作者研发了NYZ-1自动调压脉冲射水器,该设备实现了泥沙处理的自动化控制,降低了劳动强度,提高了工作效率,取得了显著的社会效益和经济效益。

世博中心水消防系统设计概述

简要介绍世博中心水消防系统的设计。本工程采用的水消防系统包括:室内外消火栓灭火系统、自动喷淋系统、高大净空喷淋系统、大空间洒水系统、大空间射水系统、舞台雨淋系统、闭式卷帘冷却水幕系统等;重点介绍世博中心五大功能分区的水消防设计,包括共享大厅、多功能厅、大会堂、国际会议厅、宴会厅等;总结世博中心的设计经验,提出在超出规范范围或条件复杂情况下,引入性能化水消防系统设计的理念。

水厂加氯系统技术改造实践

根据沙口水厂的生产实际情况,对加氯机量程及射水器搭配使用方式进行了改造,同时增加了系统远程控制功能。通过改造,使水厂加氯系统更加准确地自动控制投药量,降低了药耗及射水器用水量,提高了生产效率。

家用自控式臭氧水质净化处理装置

一种家用自控式臭氧水质净化处理装置，包括：前置过滤器、射水器、臭氧混合筒和过滤器，其特征在于：过滤器筒体内所设过滤材料层厚度不低于120mm，过滤材料层包括：生物活性炭层、沸石层、载银活性炭层、石英沙层、活性碳纤维棉层；装置的进水口设置有电磁阀，过滤器贮水腔内设有一可控制进水电磁阀的液位传感器。本装置设计科学，结构合理，其对自来水的净水处理效果完全达到了联合国世界卫生组织明确规定的生活饮用水标准，本发明的优点还在于整个装置的进水控制是根据贮水腔内水位状态进行的，

Research of chemical induction unit on mixing effect and chlorine saving

Rapid mixing and chlorine saving are two important problems that most drinking water industries are focus on, and this paper adopts chemical induction unit to compare with water jet injector to study what merits chemical induction unit has. The experiment chose coefficient of variability of chlorine concentration to evaluate the mix effect and used chlorine consumption to compare the two equipments. Distribution reservoir experiments show that chemical induction unit can completely mix chlorine less than 6.2 seconds and water jet injector can not completely mix in 3 minutes. Mixing pool experiments show that chemical induction unit can save chlorine compared with water jet injector, and can save more if more chlorine is consumed.

Numerical investigation of optimal geometry parameters for ejectors of premixed burner

An ejector of low NO~ burner was designed for a gas instantaneous water heater in this work. The flowing and mixing process of the ejector was investigated by computational fluid dynamics （CFD） approach. A comprehensive study was conducted to understand the effects of the geometrical parameters on the static pressure of air and methane, and mole fraction uniformity of methane at the outlet of ejector. The distribution chamber was applied to balance the pressure and improve the mixing process of methane and air in front of the fire hole. A distribution orifice plate with seven distribution orifices was introduced at the outlet of the ejector to improve the flow organization. It is found that the nozzle exit position of 5 mm and nozzle diameter d 〉1.3 mm should be used to improve the flow organization and realize the well premixed combustion for this designed ejector.

Performance and Optimization of 10 Gb/s Electroabsorption Modulator in Short Transmission

Transmission performance of electroabsorption modulator in 10 Gb/s transmission systems has been simulated and analyzed under the condition of taking into account the chirp,extinction ratio, transmissivity and rise/fall time.Results show that short transmission distance without EDFA after EAM can be used in future metropolitan area network,but the transmissivity must be carefully considered. The sampling time range and decision level can be optimized to reduce the bit error ratio.

Investigations on the Heat Flux Rates in Superheated Water Jet Evaporators

When a liquid undergoes sudden reduction in the surrounding pressure below its saturation pressure, the liquid then enters in a metastable state. In order to regain equilibrium, part of the liquid evaporates quickly in a phenomenon called ＂flash evaporation＂, and the excess sensible heat contained in the liquid is converted into latent heat of vaporization. Therefore, temperatures of both the liquid and the generated vapor decline to the saturation temperature for the reduced pressure. As the heat and mass transfer occur in direct contact between the liquid and its own vapors, the process involves a very high heat transfer rate which makes it suitable for exchanging heat between sources of relatively small temperature difference. Moreover, dispensability of the heat exchange surfaces in this process is a considerable advantage as these surfaces constitute major part of the total system expenses in addition to the associated maintenance problems, especially when dealing with corrosive fluids such like seawater in the thermal desalination processes and in the OTEC （ocean thermal energy conversion） systems. This paper reports on the heat flux variation profiles during the flash evaporation of superheated water jets at various flow conditions. Heat flax was found to grow with time attaining a peak value before it starts to decrease monotonically.

Contour Laser Guiding for the Mechanized ＂Vallerani＂ Micro-catchment Water Harvesting Systems

Mechanized construction of micro-catchments for water harvesting （WH） was successfully tested in the Badia （dry rangeland） areas in Syria and Jordan, using the ＂Vallerani＂ plow, model Delfino （50 MI/CM）, manufactured by Nardi, Italy. The plow was able to construct intermittent and continuous contour ridges, and could potentially be used to rehabilitate degraded rangelands. However, one major issue for large-scale implementation is the high cost and time required to manually identify contours for the plow to follow. Most existing auto-guiding systems, as usually used in road construction and agricultural land leveling, were expensive or impractical. The objective, therefore, was to add, adapt, and evaluate an auto-guiding system to enable a tractor to follow contours without demarcation through conventional surveying. A low-cost Contour Laser Guiding （CLG） system, with specifications that suit the contour ridging in undulating topographic conditions of dry rangelands, was chosen, adapted, mounted, and tested, under actual field conditions. The system consisted mainly of a portable laser transmitter and a tractor-mounted receiver, connected to a guidance display panel. The system was field-tested on 95 ha of land where the system capacity was determined under different terrains, slopes （1-8%）, and ridge spacings （4-12 m）. The easy adaptation and implementation of the CLG to the ＂Vallerani＂ unit tripled the system capacity, improved efficiency and precision, and substantially reduced the cost of constructing micro-catchments for WH. The system is recommended for large-scale rangeland rehabilitation projects in the dry areas, not only in West Asia, but worldwide.

Acoustic Emission Properties of Concrete Slab During Fatigue Testing with a Running-Wheel Load

AE （acoustic emission） signals from concrete slab during fatigue testing with a running-wheel load were evaluated. The signals were recorded by remote sensors connected to a computer network. The sensing equipment consisted of 60 kHz resonant-type AE sensors mounted on a reinforcing steel bar as a waveguide, together with a 16-channel sensor highway AE system. Because the detected AE signals included periodic mechanical noise from the motion of the wheel, these noises were eliminated by means of signal processing. The AE waveguide measurement over a length of 3 m detected fractures as vertical and horizontal cracks in the RC （reinforced concrete） slab. Those cracks were analyzed by correlating AE parameters with macroscopic distortions and the numbers of fatigue cycles. In the AE events and AE energy, two types of AE phenomena, active region and inactive region, were observed during fatigue testing. The vertical cracks were characterized by an AE amplitude of 58 dB, a peak frequency of 30 kHz, and a ratio of the rise time to the maximum amplitude value （RA） of 100. The horizontal cracks were characterized by an AE amplitude of 85 dB, a peak frequency of 60 kHz, and an RA value of 10.

Research on the Mechanism of Impedance Matching for Underwater Acoustic Transmitter based on Mathematical Modelling and Corresponding Balance Transformer

With the progress of power transmission technology, it is necessary for researchers to conduct related research on impedance matching. In this paper, we conduct research on the mechanism of impedance matching for underwater acoustic transmitter based on mathematical modelling and corresponding balance transformer. To realize underwater acoustic signal of wide band and high power emission, in addition to need the bandwidth performance good transducer array yuan, to a large extent also depends on a good matching between the transducer and amplifier. The result shows the feasibility and robustness of our designed system.

信息

最小电脑日前,世界上最小的计算机——"空间立方体"面世。空间立方体的大小是2×2×1.7英寸,大致上与一颗大骰子差不多,其金属底盘"完全像岩石一样坚硬",确保能够抵御宇宙岩石的撞击。

Experimental Study on the Interaction of Fine Water Spray with Liquid Pool Fires

An experimental study of the interaction of a fine water spray with liquid pool fires was performed. Spatially resolved droplet size, velocity distributions, and volume flux of the fine water spray have been obtained in two types of pressure-atomized fine spray, using LDAIAPV technology. A method to correct for the presence of droplets is presented and used to determine the heat release rate using a cone calorimeter system, the effects of water spray application on the heat release rate for liquid pool fires were studied. It was found that the volume flux of the water spray is an important factor to determine the liquid pool fire behavior. For the current experimental conditions, the flame was enlarged when lower volume flux of water is used, and suppressed significantly when larger volumes of water are used. Two opposing mechanisms compete when water sprays are applied, which is more complex than the halon agents, such as 1301. The combustion enhancement becomes insignificant when water sprays with the proper characteristics such as adequate volume flux are applied to the diffusion flame in a confined space.

Theoretical and experimental investigation on a liquid-gas ejector power cycle using ammonia-water

The purpose of this paper is to investigate a novel power cycle using low-temperature heat sources such as oceanic-thermal, biomass as well as industrial waste heat. Both a reheater and a liquid-gas ejector are used in this ammonia-water based cycle. Energy analysis and parametric analysis are performed to guide the theoretical performance and experimental investigation is done to verify the theoretical results. The results show that the generator pressure, heating source temperature and turbine outlet depressurization made by the ejector can affect the cycle performances. Besides, the experimental thermal efficiency is much lower than the theoretical one on account of the heat losses and irreversibility. Moreover, the performance of liquid-gas ejector is affected by primary flow pressure and temperature.

Experimental and numerical investigation of a solar eductorassisted low-pressure water desalination system

Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water resources. The efficiency and productivity of these systems are however low, in part because the heat of evaporation has to be transferred as waste heat to ambient air during condensation. In order to maximize energy regeneration during condensation we propose an educator based system that lowers the evaporation process temperature by reducing pressure. The feasibility of the educator assisted passive solar desalination system is investigated using a detailed computational fluid dynamics analysis complemented by experiments. The study focuses in particular on the ability of the new design to lower the required evaporation temperature and thereby reduce the energy intensity of the process. Two configurations, with open and closed educator, are investigated and a detailed analysis of the thermofluid processes is presented. The configuration with a closed educator installed outside the evaporation chamber shows very promising performance. The proposed system can maintain the maximum temperature and pressure in theevaporation chamber below the desirable temperature and pressure thresholds （30 ℃ and 5 kPa）. The analysis and experimental data also show it is possible to further reduce energy requirements by reducing the motive water flow rates.

Non-Contact Measurements of Water Jet Spreading Width with a Laser Instrument

Jet spreading width is one of the important characteristics of water jets discharging into the air.Many researchers have dealt with measuring this width,and contact measuring methods on the water jet surface were employed in a lot of the cases.In order to avoid undesirable effects caused by the contact on the jet surface,we introduce non-contact measuring methods with a laser instrument to the measurements of jet spreading width.In measurements,a transmitter emits sheet-like laser beam to a receiver.The water jet between the transmitter and the receiver interrupts the laser beam and makes a shadow.The minimum and maximum values of the shadow width are measured.In addition,pictures of the water jet are taken with a scale,and the shadow width is measured from the pictures.The experiments on various needle strokes were performed.Three kinds of width consistent with the jet structure were obtained.In the results,it can be concluded that our non-contact measuring methods are feasible.The data of jet spreading widths and jet taper were obtained and are useful for future applications.

Near fields scattered by an underwater finite cylindrical baffle

In this work,acoustic vector characteristics of near fields scattered by an underwater finite cylindrical baffle are investigated theoretically and experimentally.The analytic expressions for the scattered pressure and particle velocity are derived using the elastic thin shell theory.Calculations are presented for the scattered near fields of the pressure,the particle velocity and the intensity.It is found that the pressure and the particle velocity fields near the surface of the cylindrical baffle are characterized by complex interference structure,particle velocity directions and the source bearings are not consistent.The phase difference between the pressure and the particle velocity is not zero and the intensity vector does not reflect the sound bearings.It can be noted that the distortions of the fields will make the original vector signal processing method based on the free space assumption be no longer applicable in the presence of the cylindrical baffle.These results can serve as a basis of the application for the acoustic vector sensor on board.