The flame retardant mechanism of polyolefins modified with chalk and silicone elastomer

This paper presents the current understanding of the flame retardant mechanism of Casico?. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from ¹³C MAS‐NMR and ²⁹Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd.     

Orthogonal space-time block codes: maximum likelihood detection for unknown channels and unstructured interferences

Space-time coding (STC) schemes for communication systems employing multiple transmit and receive antennas have been attracting increased attention. The so-called orthogonal space-time block codes (OSTBCs) have been of particular interest due to their good performance and low decoding complexity. In this paper, we take a systematic maximum-likelihood (ML) approach to the decoding of OSTBC for unknown propagation channels and unknown noise and interference conditions. We derive a low-complexity ML decoding algorithm based on cyclic minimization and assisted by a minimum amount of training data. Furthermore, we discuss the design of optimal training sequences and optimal information transfer to an outer decoder. Numerical examples demonstrate the performance of our algorithm.     

Age-dependent variations in the sexual preference of male rats

Male rats were tested for their sexual preference behavior at either 37, 70, 90, or 150 days of age on three different occasions; while still sexually naive, after sexual experience with a receptive female, and while sexually aroused by having initiated copulation. These tests resulted in the following findings: a) 37-day-old sexually naive males showed a preference for other males and failed to show a preference for either sex after exposure to females; b) 70- and 90-day-old males showed a statistically significant preference for the female after acquiring sexual experience; c) 150-day-old animals showed a female-oriented preference only after being sexually aroused with two intromissions preceding the preference test, and d) none of the age groups tested showed a female-oriented preference without previous exposure to females. It was then concluded that a) female-oriented behavior requires sexual experience and b) the effects of experience varies with age.     

关于空调水系统节能的探讨

以空调冷冻水系统的节能为例 ,探讨空调系统节能的途径、存在的问题及解决办法     

金属钝化剂的合成和应用

简要介绍了金属钝化剂的品种和合成方法及在PE、PP、PS等聚合物材料上的应用。     

Mobile robot localization: integrating measurements from atime-of-flight laser

This paper presents an algorithm for environment mapping by integrating scans from a time-of-flight laser and odometer readings from a mobile robot. The range weighted Hough transform (RWHT) is used as a robust method to extract lines from the range data. The resulting peaks in the RWHT are used as feature coordinates when these lines/walls are used as landmarks during navigation. The associations between observations over the time sequence are made in a systematic way using a decision directed classifier. Natural geometrical landmarks are described in the robot frame together with a covariance matrix representing the spatial uncertainty. The map is thus built up incrementally as the robot moves. If the map is given in advance, the robot can find its location and navigate relative to this a priori given map. Experimental results are presented for a mobile robot with a scanning range measuring laser having 2-cm resolution. The algorithm was also used for an autonomous plastering robot on a construction site. The sensor fusion algorithm makes few erroneous associations     

Infrared absorption in Li-intercalated tungsten oxide

Thin films of amorphous and polycrystalline tungsten oxide were produced by reactive dc magnetron sputtering and nanocrystalline films were deposited by advanced gas evaporation. The films were submitted to electrochemical intercalation of Li ions before infrared reflectance measurements were carried out. For crystalline films, the reflectance in the wavelength region 10–30 μm increases upon intercalation, indicating an increasing free-electron contribution. On the other hand, all the films display an increased absorption at wavelengths less than 10 μm when intercalated. The thermal emittance could be varied from about 0.5 to 0.7–0.75 by intercalation in films with thicknesses in excess of 1 μm. Both absorption and interference contribute to the emittance contrast.     

PYY in developing murine islet cells: comparisons to development of islet hormones, NPY, and BrdU incorporation

Exhaustive characterizations of antisera to the structurally related peptides pancreatic polypeptide (PP), neuropeptide Y (NPY), and peptide YY (PYY) enabled us to establish the developmental pattern of these peptides in rat and mouse pancreas. PYY was the earliest detectable peptide and was present in all early appearing endocrine cell types. NPY appeared later and occurred exclusively in a subpopulation of insulin cells, whereas PP cells arose latest. At the earliest stage studied, all endocrine cells stored PYY. Most of these cells also contained glucagon. Subsequently, the endocrine cells comprised glucagon+PYY cells and glucagon+PYY+insulin cells. Later, cells storing either only insulin or insulin+PYY appeared. Quantitations of the relative numbers of these cell populations during development were consistent with a precursor role of triple-positive (insulin+glucagon+PYY) cells. Moreover, bromodeoxyuridine (BrdU) injections at E15.5 showed that a large percentage of triple-positive cells were in S-phase and therefore were actively dividing, whereas almost no pure insulin cells or insulin+PYY cells synthesized DNA at this time. These results suggest that PYY-positive endocrine cells may represent precursors for mature islet cells.     

A special-case surface voltage gradient formula [for substationdesign]

In the electrical design of a high-voltage substation, the designer needs a simple and reliable tool, preferably a closed-form formula, when calculating the surface voltage gradient of line segments within the substation since the surface voltage gradient is the governing parameter of the corona performance. This paper presents a derivation of a closed-form formula for calculation of the maximum surface voltage gradient of a special line configuration, namely a horizontal AC three-phase line configuration with bundle conductors consisting of three sub-conductors in a horizontal arrangement. The formula has been verified against exact calculations and was found to have an error less than 5% for all practical combinations of the conductor radius, the sub-conductor spacing, the phase distance, and the height above earth