圆柱壳大开孔极限载荷的试验

通过试验研究分别用两倍弹性斜率法、双切线法确定了内压作用下圆柱壳大开孔结构（ｄ／Ｄ≥０．５）的极限载荷。同时,由爆破试验得到该大开孔结构的爆破压力及爆破发生的部位。结果表明,对于本文所研究的开孔率大于０．５的薄壁容器,其横向对称面上的极限载荷均大于纵向对称面上的极限载荷,即纵向对称面是大开孔结构的薄弱环节。     

Quantitative models on corrosion fatigue crack growth rates in metals: Part II. application of fatigue crack growth rate modeling for nickel-based superalloys at elevated temperatures

Approaches to predict da/dN-àK for environmental situations; including empirical interpolative equations, linear superposition of mechanical fatigue and time-based environmental cracking, and mechanism-based models; are presented. For several material-environment systems, these models were incorporated in fracture mechanics life prediction methods, and successes have been reported in evaluating the corrosion fatigue contribution. Considerable uncertainties are, however, associated with these models. The linear superposition analysis is emphasized; material-environment systems that are severely environment-sensitive should be adequately described by this method. Direct and indirect methods exist to define time-based crack growth rates for use in linear superposition predictions of da/dN. The linear superposition approach is effective, but only for those cases where K_ISCC is high relative to typical flawed component stress intensity levels. Empirical curve-fit models require an extensive environmental crack growth rate data base, which are costly to develop, and are effective for interpolations but not predictions of fatigue crack growth data. Mechanism-based models for broad predictions of cycle-time dependent da/dN versus àK, and other variables such as frequency or hold time, are in an infant state.     

Logical and diversity combining in FH/SSMA packet radio networks

We propose the logical and diversity combining in slotted frequency-hopped spread spectrum multiple access (FH/SSMA) packet radio networks. The proposed diversity scheme employs the symbol-by-symbol logical AND operation between the currently received packet and the previously combined packet. Our results show that the proposed low-complexity diversity combining scheme provides a significant performance improvement over existing diversity combining schemes     

Urea-assisted hydrothermal synthesis of MnMoO4/MnCO3 hybrid electrochemical electrode and fabrication of high-performance asymmetric supercapacitor

Transition metal molybdates/carbonates and hybrid nanomaterials have attracted great attention in en-ergy storage applications because of their enriched redox a...     

A movable safety zone scheme in urban fiber-optic microcellularsystems

We consider an urban fiber-optic microcellular system in which a cigar-shaped cell consists of several microzones with their own antenna sites connected to a central station through optical fibers. To increase the efficiency of radio resources and reduce unnecessary handoffs between microzones, we propose a movable safety zone scheme. A safety zone is a virtually guarded area that does not permit cochannel interference. Outside the safety zone, cochannels can be reused. The safety zone can move under the condition that its user does not meet cochannel interference as he moves to an adjacent microzone. Considering user mobility characteristics in the cigar-shaped cell, we analyze and evaluate the proposed system in terms of intracell and intercell handoff rates, blocking probability, intracell call-dropping probability, and channel reuse parameter. The proposed system can handle a traffic capacity of about 12 Erlangs for seven traffic channels under a call blocking probability of 1% and generates a negligible number of intracell handoffs compared with those of intercell handoffs     

煤层气的封存与富集条件

在水文地质条件简单的地区,煤层气的封存主要取决于煤层气富集区的构造及盖层岩性。通常情况下,压性断层可使煤层甲烷增多,张性断层使其降低。但在远离张性断层面的两侧,一般形成两个对称的平行条带状构造应力高压区,使得煤层甲烷含量相对升高,成为阻止煤层甲烷进一步向断层运移的天然屏障。背斜构造的中和面以上及向斜构造的中和面以下常会出现煤层甲烷的富集。依据煤层气盖层的排驱压力、渗透率等值,盖层可分为屏蔽层、半屏蔽层和透气层,它们在不同的构造发育区,其封盖性能不同,由此可划分出9类不同的构造封盖层岩性组合类型。平顶山矿区的实例分析表明:Ⅰ类组合煤层气含气性最好,其次为Ⅱ类、Ⅳ类、Ⅴ类,其它类型含气性最差。     

Improvement of P-channel SOI LDMOS transistor by adapting a newtapered oxide technique

On-resistance of P-channel REduced SURface Field (RESURF) lateral double-diffused MOS (LDMOS) transistors has been improved by using a new tapered TEOS field oxide on the drift region of the devices. The new tapered oxidation technique provides better uniformity, less than 3%, and reproducibility. With the similar breakdown voltage (V_B), at V_gs=-5.0 V, the specific on-resistance (R_sp) of the LDMOS with the tapered field oxide is about 31.5 mΩ·cm ², while that of the LDMOS with the conventional field oxide is about R_sp=57 mΩ·cm². The uniformities of R_sp and V_B are less than 5 and 3%, respectively     

颗粒增强复合材料增强体颗粒分布均匀性研究

研究了高能球磨法与常规混合法对ＳｉＣｐ（Ｂ４Ｃｐ）／Ａｌ复合材料增强体颗粒分布均匀性的影响。高能球磨法使增强体颗粒弥散均匀分布于基体中,是实现增强体颗粒均匀分布的最有效的方法之一。常规混合法制备的复合材料中存在增强体颗粒的偏聚现象,颗粒偏聚程度与混粉方式和混粉时间有关,干混存在最佳混粉时间,而湿混时混合物均匀度随混粉时间延长而不断提高。     

Antifungal Activity of Bacillus velezensis CE 100 against Anthracnose Disease (Colletotrichum gloeosporioides) and Growth Promotion of Walnut (Juglans regia L.) Trees

Walnut anthracnose caused by Colletotrichum gloeosporioides is a deleterious disease that severely affects the production of walnut (Juglans regia L.). The aim of this study was to assess the antifungal and growth promotion activities of Bacillus velezensis CE 100 as an alternative to chemical use in walnut production. The crude enzyme from B. velezensis CE 100 exhibited chitinase, protease, and β-l,3-glucanase activity and degraded the cell wall of C. gloeosporioides, causing the inhibition of spore germination and mycelial growth by 99.3% and 33.6% at 100 µL/mL, respectively. The field application of B. velezensis CE 100 culture broth resulted in a 1.3-fold and 6.9-fold decrease in anthracnose disease severity compared to the conventional and control groups, respectively. Moreover, B. velezensis CE 100 produced indole-3-acetic acid (up to 1.4 µg/mL) and exhibited the potential for ammonium production and phosphate solubilization to enhance the availability of essential nutrients. Thus, field inoculation of B. velezensis CE 100 improved walnut root development, increased nutrient uptake, enhanced chlorophyll content, and consequently improved total biomass by 1.5-fold and 2.0-fold compared to the conventional and control groups, respectively. These results demonstrate that B. velezensis CE 100 is an effective biocontrol agent against anthracnose disease and a potential plant growth-promoting bacteria in walnut tree production.