Low-cost oriented preparation of ultra fine xonotlite fibers

Nanometer-sized xonotlite fibers have great potential application in many fields. The traditional method of preparing ultra fine xonotlite fibers uses the ultra fine and highly active silica as the major raw materials, which is not only expensive but also difficult to prepare the xonoflite fibers with diameters around 100 nm. In this study, the ultra fine xonotlite fibers with diameters around 100 nm were prepared by an autoclaving method. The preparation was low-cost oriented by using natural powder quartz and lime as the major raw materials. The intergrowth of the fibers formed thin shell hollow balls or ellipsoids, namely the secondary particles. The length of the nanometer-sized xonotlite fibers was around several microns. The fibers and their secondary particles were produced at 216℃ for 6 h with a continuous stirring of 300-500 r/min. Zirconium oxychloride was used as an additive. The experiments show that zirconium oxychloride has an enormous effect on the growing habit of xonotlite crystals and     

无成本、低成本节能措施在商用建筑中的应用

介绍了美国环保局(EPA)发起的“eeBuildings”项目所提出的“无成本、低成本节能措施”的思想,通过分析该项目在美国和上海的成功案例和经验,得出了无成本、低成本节能措施的特点,并进一步提出适用于上海市商用建筑的无成本、低成本的节能措施。     

房地产开发企业实施低成本战略的分析

论述了房地产开发企业实施低成本战略的必要性以及各种措施,并对实施这一战略的风险进行了简单分析,指出实施低成本战略不仅可以节省成本,获得高利润,还可以提高企业的竞争力。     

A Low-Cost Test Methodology for Dynamic Specification Testing of High-Speed Data Converters

Testing high-speed A/D converters for dynamic specifications needs test equipment running at high frequency. In this paper, a methodology to test high-speed A/D converters using low-frequency resources is described. It is based on the alternate testing approach. In the proposed methodology, models are built to map the signatures of an initial set of devices, obtained on the proposed low-cost test set-up, to the dynamic specifications of the same devices, obtained using high-precision test equipment. During production testing, the devices are tested on the low-cost test set-up. The dynamic specifications of the devices are estimated by capturing their signatures on the low cost test set-up and processing them with the pre-developed models. As opposed to the conventional method of dynamic specification testing of data converters, the proposed approach does not require the tester resources running at a frequency higher than the device-under-test (DUT). The test methodology was verified in simulations as well as in hardware with specification estimation error of less than 5%.

A new low-cost method of reclaiming mixed foundry waste sand based on wet-thermal composite reclamation

A lot of mixed clay-resin waste sand from large-scale iron foundries is discharged every day; so mixed waste sand reclamation in low cost and high quality has a great realistic significance. In the study to investigate the possibility of reusing two types of waste foundry sands, resin bonded sand and clay bonded sand which came from a Chinese casting factory, a new low-cost reclamation method of the mixed foundry waste sand based on the wet-thermal composite reclamation was proposed. The waste resin bonded sand was first reclaimed by a thermal method and the waste clay bonded sand was reclaimed by a wet method. Then, hot thermal reclaimed sand and the dehydrated wet reclaimed sand were mixed in certain proportions so that the hot thermal reclaimed sand dried the wet reclaimed sand leaving some water. The thermal reclamation efficiency of the waste resin bonded sand was researched at different heat levels. The optimized wet reclamation process of the waste clay bonded sand was achieved by investigating the effects of wet reclamation times, sand-water ratio and pH value on the reclaimed sand characteristics. The composite reclamation cost also was calculated. The research results showed that the properties of the mixed reclaimed sand can satisfy the application requirements of foundries; in which the temperature of the thermal reclamation waste resin bonded sand needs to be about 800 oC, the number of cycles of wet reclamation waste clay bonded sand should reach four to five, the optimal sand-water ratio of wet reclamation is around 1：1.5, and the pH value should be adjusted by adding acid. The mass ratio of hot thermal reclaimed sand to dehydrated wet reclaimed sand is about 1：2.5, and the composite reclaimed sand cost is around 100 yuan RMB per ton.     

一种远程控制编码芯片的ASIC研究与设计

提出了一种新型的远程控制编码芯片的电路设计,该芯片由时序控制电路、键盘矩阵扫描电路、用户码扫描电路、编码输出等电路模块组成.远程传输方式采用红外传输协议中的NEC协议,由引导码、16位地址码、8位数据码及其反码组成,可兼容市场上大部分红外传输产品,有良好的适应性.     

Gel Permeation Chromatography Calibration. I. Use of Calibration Curves Based on Polystyrene in THF and Integral Distribution Curves of Elution Volume to Generate Calibration Curves for Polymers in 2,2,2-Trifluoroethanol

Abstract

A general method is proposed for obtaining gel permeation chromato-graphic (GPC) molecular weight (MW) and hydrodynamic volume (HDV) calibration curves for polymer-solvent systems where primary polymer standards are unavailable. The method is demonstrated by using a HDV calibration curve based on polystyrene in tetrahydrofuran (THF), in conjunction with integral distribution curves of elution volume for poly(methyl methacrylate) (PMMA) in THF and in 2,2,2-tri-fluoroethanol (TFE) for the generation of a HDV calibration curve in TFE. Transformation methods for generating secondary MW calibration curves from HDV calibration curves are discussed and applied to PMMA in THF and TFE, and to poly(trimethylene oxide), poly(vinyl acetate), and certain polyamides in TFE. The utility and reliability of the secondary calibration curves are demonstrated by comparing MW average and intrinsic viscosites obtained by GPC and by the classical methods. Molecular structural differences among th polyamide samples associated with the distribution of short- and long-chain branches are discussed in relation to their secondary calibration curves.     

Treatment of Contaminated Water Laden with 4-Chlorophenol using Coconut Shell Waste-Based Activated Carbon Modified with Chemical Agents

This laboratory study investigates the performances of coconut shell waste-based activated carbon (CSBAC) in removing 4-chlorophenol (4-CP) from contaminated water. To improve its removal for target compound, the surface of CSBAC was modified with TiO₂, NaOH, and/or HNO₃. Under optimized conditions at the same initial concentration of 25 mg/L, the NaOH-treated CSBAC could remove 91% of 4-CP, compared to the HNO₃-oxidized CSBAC (60%) or the TiO₂-coated CSBAC (72%). Although the NaOH-treated CSBAC could remove 91% of 4-CP, the adsorption treatment using this adsorbent alone was unable to meet the effluent limit of lower than 1 mg/L. Therefore, subsequent biological processes are required to complement the removal of 4-CP from wastewater.     

低造价农居隔震结构研究现状综述

指出了村镇民居抗震能力较弱的事实,根据村镇民居的特点,对适用于村镇农居的低造价隔震技术进行了综述,介绍了当前这一领域研究的新进展,并提出了今后应当注意的问题,以期减少地震灾害造成的损失。     

基于低成本FPGA的AES密码算法设计

主要介绍在逻辑资源少的现场可编程门阵列（FPGA）上实现高级数据加密标准（AES）算法设计。首先描述了AES加密算法,并在FPGA上优化实现AES算法,设计结构采用多轮加密共用一个轮运算的顺序结构,加密和解密模块共用密钥扩展模块,减少资源占用,在低时钟频率下保持较高的性能。采用了16位的并行总线通信接口,利用先进先出缓冲器（FIFO）对输入输出数据进行缓存。最后通过仿真和实测表明,在50MHz时钟下加解密速率可达530Mb/s。