基于单片机构建智慧农业无线传感器网络

农田灌溉对于作物来说是必不可少的,如何根据阳光、土壤、水源分布以及作物自身的生长情况进行农田灌溉至关重要。文章基于单片机技术,使用无线传感器网络构建了一个智慧农业农田灌溉系统,对促进农作物生长起到了很大的作用。     

Effect of space velocity on the performance of methane steam reforming in a plate micro channel reactor

A 2 D numerical simulation is conducted on the steam reforming reaction in a plate micro reactor by applying the general finite reaction rate model in the CFD software FLUENT and a detailed surface reaction kinetics mechanism. Catalyst space velocity(CSV) and gas space velocity(GSV) inlet mixture impact on the reaction is discussed. During the calculations, the space reaction effect is ignored and only the reaction of CH4 on catalytic surface is taken into account. Calculation results show that lower CSV or GSV can achieve high efficiency conversion of CH4 and H2 output; besides CSV and GSV, channel height is an important factor for the reforming performance of plate micro reactors.     

Analysis and simulation of volume conduction channel for implantable devices

According to closed loop communication system design of implantable devices and the communication problems, a data communication model based on volume conduction is proposed; volume conduction channel’s basic characteristic is analyzed, namely, when working frequency of volume conduction channel runs in kHz grade, biological background signal interference is insignificant. volume conduction channel can be approximated as additive white gaussian noise channel (AWGN); derived under two dimensional modulation channel capacity formula. Thus, two level modulation of channel capacity could be effective at very low signal to noise ratio (SNR), while multi level modulation should be used at high SNR. Finally, using SystemView of channel simulation, the results show that the two level modulation is better than multi level modulation and verify the effectiveness of the proposed method.     

冬小麦不同穗型对产量构成因素的作用

为了提高小麦产量,以多穗型、中穗型和大穗型小麦为材料,通过不同密度对产量结构的调查、分析和探讨及其有关性状的研究,找出小麦生产中存在的主要问题,证明小麦产量构成因素中,决定产量的主导因子是穗数,其次是千粒重,最后是穗粒数。并提出今后小麦高产育种策略应增加有效分蘖,稳定千粒重,挖掘穗粒数的潜力;并对今后黄淮北片麦区小麦高产育种途径进行了探讨。     

Effect of amlodipine on echocardiographic variables in cats with systemic hypertension

Left ventricular hypertrophy signals a poor prognosis in hypertensive humans. Cardiac disease is common in cats with systemic hypertension. The aims of this study were to characterize the echocardiographic findings of cats with systemic hypertension and to determine if reducing the degree of hypertension is associated with resolution of cardiac hypertrophy. Echocardiographic examinations were performed on 19 cats with naturally occurring systemic hypertension. Fourteen of these cats were subsequently studied after a minimum of 3 months of treatment with the antihypertensive agent amlodipine. Hypertensive cats had a significantly thicker interventricular septum in both systole and diastole, thicker left ventricular free wall in both systole and diastole, and larger left atrium compared to the published normal values and 74% (14/19) of the cats met criteria for left ventricular hypertrophy (diastolic septal or free-wall thickness > 0.60 cm). Systolic blood pressure was lower after treatment (217 +/- 25 mm Hg, range: 180-275 mm Hg; and 142 +/- 27 mm Hg, range: 90-200 mm Hg). No difference was found in any of the echocardiographic measurements between the untreated and treated cats, although more cats had ventricular hypertrophy before treatment (11/14) than after initiating amlodipine (6/14; P = .006). Ventricular hypertrophy is common in hypertensive cats and may resolve after the initiation of amlodipine.     

Effects of levcromakalim on pulmonary arterial endothelial cells and smooth muscle cells exposed to hypoxia

AIM:To explore the effects of levcromakalim(Lev) on pulmonary arterial endothelial cells (PAEC) and smooth muscle cells (PASMC) exposed to hypoxia and the mechanisms involved.METHODS:The effects of Lev on [Ca²⁺]_i, and expression of PKC_α, eNOS, iNOS and PDGF-B mRNA and protein levels were observed. The nitrite (NO₂^-) and entothelin-1(ET-1) concentrations in supernatant in cultured PAEC and PASMC were measured. The proliferation and apoptosis of PASMC was also detected.RESULTS:When PASMC were exposed to hypoxia, Lev reduced concentration of ET-1 in cultured cell supernatant, lowed the expression of PKC_α, iNOS and PDGF-B both at mRNA and protein levels, decreased [Ca²⁺]_i concentration, increased proliferation and promoted the apoptosis in PASMC. However, in the presence of Lev, the [Ca²⁺]_i concentration was not changed in the hypoxic PAEC. The NO₂^- concentration in cultured cell supernant and expression of eNOS at mRNA and protein levels in hypoxic PASMC and PAEC were also unchanged. The downregulated ET-1 activity in PASMC and PAEC and proliferation in PASMC involved in the inhibition of PKC_α signaling pathway.CONCLUSIONS:Lev reduce some disadvatage effect of hypoxia on PASMC and PAEC. The mechanism of Lev action may partly involve in the downregulation of PKC_α signaling functions.     

Influences of Ca2＋ antagonist on the mRNA levels of L-type Ca2＋ channel and Na＋-Ca2＋ exchanger in the atria of hypertensive rats

AIM: To investigate the mRNA changes of L-type Ca²⁺channel α_1Csubunit (CaL-α_1C) and Na⁺-Ca²⁺ exchanger (NCX) in the atria of renovascular hypertensive rats. METHODS: Two-kidney one-clip Goldblatt hypertensive Sprague-Dawley rats were divided into three groups 1 week after operation, HD group was treated with 250 mg/d diltiazem, LD group was treated with 50 mg/d diltiazem, control group (C group) was treated with vehicle. After 4 weeks treatment, semiquantitative RT-PCR was used to estimate the mRNA changes of CaL-α_1Cand NCX, and GAPDH was used as internal control. RESULTS: Systolic blood pressure in LD group was comparable with C group, and that in HD group was decreased to normal level after diltiazem treatment. In C group, CaL-α_1C mRNA level were 2.5, 2.4 and 2.1 times of S, HD and LD group, and NCX mRNA level were 1.9, 1.6 and 2.1 times of S, HD and LD group. There were no significant difference in the mRNA level of CaL-α_1Cand NCX among S, HD and LD group. CONCLUSION: The mRNA levels of CaL-α_1Cand NCX are upregulated in the atria of hypertensive rats. Ca²⁺ antagonist inhibites their upregulation independent of blood pressure.     

黄河干流输水能力对南水北调西线调水量的影响

本文针对黄河干流防凌、城市防洪、平滩流量的约束,计算常流量下的干流最大可能输水能力,结合干流节点不同来水频率,得到相应来水频率下的南水北调西线最大可能调水量。可为南水北调西线工程规划和调度提供参考。     

滦河下游河道建设项目的防洪影响评价问题

本文结合滦河下游河道的闫庄铁矿工程的具体情况,对河道建设项目防洪评价的基本工作进行了研究探讨。通过分析工程实施前后河道设计洪水水位和流量的变化,评价了该工程对滦河下游河道防洪的影响。结果表明:各个控制断面由闫庄铁矿工程所导致的水位和流量变化幅度都是非常小的,并且主要是在工程所在位置上游的附近12.5km范围内。水位变化最高只有0.12m,流量变化的幅度更是不超过0.092‰。因此,闫庄铁矿工程建设方案实施后,基本上不会对河道行洪产生影响,这为闫庄铁矿工程河道建设项目的实施提供了依据。     

基于虚拟仪器技术的远程发动机测试诊断系统设计

提出了一种基于虚拟仪器测试汽车发动机性能的新方法,建立了基于虚拟仪器的汽车发动机性能远程测试诊断系统。该系统采用PC-DAQ方案,通过多传感器采集和数据融合,配以车载式PC机、数据采集卡和GPRS无线上网卡为主要硬件平台,以LabVIEW为软件开发平台,构成了汽车发动机性能的数据采集控制仪器。本文从硬件构成和软件功能上对整个系统的建立进行了详细介绍。实践表明,该检测系统具有较高的精度。