CIB working commission W87

Jens Knocke of the National Swedish Institute of Building Research and coordinator of the commission of 75 experts from 25 countries demonstrates how 'builders' all over the world are open to legal action if their product, the building, with its installations and landscaping fails to satisfy any of a long range of 'user' requirements.     

Characterization of Cement-Based Materials Using Diffuse Ultrasound

The objective of this research is to develop a quantitative understanding of the propagation of ultrasonic waves in cement-based materials by examining specimens made of a portland cement-paste matrix and glass bead “aggregate.” The incident ultrasonic waves are broadband and contain wavelengths on the order of the glass bead scatterers. Experimentally measured ultrasonic waves are interpreted using diffusion theory to quantitatively measure dissipation and diffusion coefficients as functions of frequency and microstructure. These results provide a basic understanding of the effect of some features of the microstructure on the propagation of ultrasonic waves, as well as supplying a first step in the characterization of distributed damage using ultrasonic methodologies.     

Safety of food contact silicone rubber: Liberation of volatile compounds from soothers and teats

The release of volatile compounds from soothers and teats made from silicone rubber has been investigated. Firstly, measurements of the total release of volatiles were performed according to the method in the draft European standard (CEN). Weight losses of 0.17-0.80% after four hours at 200 °C were observed using gravimetric measurements. One product had a weight loss above the proposed CEN limit of 0.5%. Secondly, the volatile compounds were identified using a thermal desorption/cold trap injector on a gas chromatograph equipped with infrared spectroscopic (IR) and mass spectrometric (MS) detectors. The main compounds were siloxane oligomers and aliphatic hydrocarbons. One teat released about 0.1 mg diethyl phthalate (DEP), which is considered to be quite a high quantity. Limited amounts of the antioxidant 3,5-di-t-butyl-4-hydroxytoluene (BHT) were found in most samples.     

The oxidative dehydrogenation of ethane by perovskite type catalysts containing oxides of strontium, cerium and ytterbium

Compounds with the general formula SrCe_1−xYb_xO_3-0.5x have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), temperature programmed reduction (TPR) and BET, and tested for catalytic activity with respect to dehydrogenation of ethane to ethene. XRD indicates that the solubility limit of Yb₂O₃ in SrCeO₃ is about 10 %, above which a second phase is formed. Furthermore, Yb:SrCeO₃ is unstable in the presence of CO₂ as it reacts to SrCO₃ and Yb:CeO₂. TPR measurements indicate that Ce may be reduced from tetra- to the trivalent state. BET measurements yielded specific surface areas of approximately 1m²/g. The different catalyst compositions were tested in a continuous flow tubular reactor with two different partial pressures of oxygen at 500, 600 and 700 °C. A maximum yield of 49 % was obtained at 700 °C. Possible reaction mechanisms are discussed.     

A Comparative Study Of Discomfort Caused By Indoor Air Pollution,Thermal Load And Noisec

The relative importance of sensory air pollution, thermal load and noise was studied under controlled conditions in two identical environmental chambers. In one chamber subjects were exposed to various levels of either thermal load or poor indoor air quality. For each condition tested in this chamber, the subjects were exposed to a number of noise levels in an adjacent chamber with neutral thermal conditions and good indoor air quality in order to determine a noise level causing the same degree of discomfort. A total of 68 comparisons of the conditions in the two chambers were made by the same group of 16 subjects after one-minute exposure in each chamber. In the operative temperature range of 23–29°C, a 1°C change in operative temperature was found to have the same effect on human comfort as a change in perceived air quality of 2.4 decipol or a change in noise level of 3.9 dB. For levels of perceived air quality up to 10 decipol, a 1 -decipol change in perceived air quality had the same effect on human comfort as a change in noise level of 1.2 dB. A relationship between traffic noise level and percentage dissatisfied was established     

A Low-Power Heterogeneous Multiprocessor Architecture for Audio Signal Processing

This paper describes a low-power programmable DSP architecture that targets audio signal processing. The architecture can be characterized as a heterogeneous multiprocessor consisting of small instruction set processors called mini-cores as well as standard DSP and CPU cores that communicate using message passing. The mini-cores are tailored for different classes of filtering algorithms (FIR, IIR, N-LMS etc.), and in a typical system the communication among processors occur at the sampling rate only.The mini-cores are intended as soft-macros to be used in the implementation of system-on-chip solutions using a synthesis-based design flow targeting a standard-cell implementation. They are parameterized in word-size, memory-size, etc. and can be instantiated according to the needs of the application. To give an impression of the size of a mini-core we mention that one of the FIR mini-cores in a prototype design has 16 instructions, a 32-word × 16-bit program memory, a 64-word × 16-bit data memory and a 25-word × 16-bit coefficient memory.Results obtained from the design of a prototype chip containing mini-cores for a hearing aid application, demonstrate a power consumption that is only 1.5–1.6 times larger than a hardwired ASIC and more than 6–21 times lower than current state of the art low-power DSP processors. This is due to: (1) the small size of the processors and (2) a smaller instruction count for a given task.     

德国普拉特ELEC 2C山顶型无线电监测站简介

随着无线电技术的飞速发展和无线电设备的广泛应用，有一些无线电监测站希望拥有能监测高于3GHz频段的设备。在此，笔者给大家介绍一下德国普拉特公司（Plath GmbH）所开发和集成的ELEC 2C山顶型宽频带无线电监测站。     

Postischemic hyperactivity in the Mongolian gerbil correlates with loss of hippocampal neurons.

Gerbils show a postischemic increase in locomotor activity that correlates to the extent of neuron loss in the hippocampal CA1 subfield. It has been suggested that this hyperactivity is predictive of neuron loss in the CA1. In this study the correlation between postischemic hyperactivity and neuron loss in several hippocampal subfields was investigated, and the theory that the hyperactivity is due to a reduced ability for spatial navigation was evaluated. Significant correlations were found between hyperactivity and neuron loss in several hippocampal subfields; the correlation was stronger for the CA3 than for the CA1 subfield suggesting that postischemic hyperactivity can be used as a predictor of neuron loss in the CA3 rather than in the CA1. From observations of the pattern of hyperactivity within the test arenas and during the test period, this study challenges the spatial mapping theory of postischemic hyperactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)