封闭型钢筋切断机操纵机构的故障分析

封闭型钢筋切断机操纵机构的故障分析太原重型机械学院机器厂王伯平操纵机构是钢筋切断机的主要部件，用来对切割钢筋工作运动的控制，它直接关系着切断机的使用性能和工作运动的准确与可靠。由于钢筋切断机工作中的冲击载荷较大，所以操纵机构在使用中有出现故障的现象，...     

新型PC钢棒自动切断机的研制与开发应用

在传统手动砂轮切断机上经过改进，研制出一种能实现自动控制，高效、节能的全新自动PC钢棒砂轮切断机。这种新型PC钢棒自动切断机可与冲断式PC钢棒切断机的功能相媲美，而且经济效益显著。     

钢筋工干活经验技巧窍门集锦（4）

八 下料 现在没人使用克子和铁锯了．砂轮切割机也很少使用。工地都是以钢筋切断机为主。那么，钢筋切断机你用好了么？常见的做法是．就地摆放钢筋切断机．或者在切断机下面垫上一两层砖或木方木板．在切断机的一侧，钉一条大板，十多米长．下料时当做定尺。你不认为这种古老的方法太落后太笨拙了吗？最大的缺点是隔断了通道．且人干活太猫腰容易疲劳。     

基于VB的钢筋切断机飞轮转动惯量计算模型

钢筋切断机工作过程中，由于切割瞬间工作阻力较大，使电机的运动状态变化较大。电机在工作过程中的速度降是衡量钢筋切断机设计质量的重要指标之一，相关国家标准对其作了严格规定。飞轮转动惯量的选择及形状设计对于改善切断机的工作状态十分重要。本文建立了钢筋切断机飞轮转动惯量设计的通用计算模型，并采用VB程序编制了飞轮设计的总程序。     

对钢筋切断机发展的几点看法

钢筋切断机是钢筋加工必不可少的设备之一，它主要用于房屋建筑、桥梁、隧道、电站、大型水利等工程中对钢筋的定长切断。钢筋切断机与其它切断设备相比，具有重量轻、耗能少、工作可靠、效率高等特点，因此近年来逐步被机械加工和小型轧钢厂等广泛采用，在国民经济建设的各个领域发挥了重要的作用。１　发展过程 太原重机学院机器厂是最早生产钢筋切断机的厂家之一，１９５８年首先引进苏联的卧式钢筋切断机图纸，开始生产了全国第一台钢筋切断机，现生产的 ＧＱ４０Ａ型就是其改进型。原机型体积较大，重１０００多 ｋｇ，电机功率７．５…     

GQ40E全封闭钢筋切断机设计及其特点

ＧＱ４０Ｅ全封闭钢筋切断机设计及其特点高蕊，孟进礼，章友文（太原重机学院机器厂）目前国内钢筋切断机普遍存在以下几个主要问题：（１）全封闭结构钢筋切断机均采用减速箱结构用螺栓连接，不仅刚性差而且还增加了结合面处的加工，合盖后常常从该处漏油；而整体式结构...     

螺纹钢筋调直切断机的安装、使用与维护

近年来，公称直径在6～14mm范围内的热轧带肋Ⅱ级盘条钢筋在建筑施工中大量使用，螺纹钢筋调直切断机已经成为工业与民用建筑行业不可缺少的设备。由于热轧带肋钢筋强度高、硬发大且表面带肋，对调直切断机的使用要求更加严格，下面谈谈如何做好螺纹钢筋调直切断机的安装调试、使用与维护。     

钢筋切断机切断过程分析及最大冲切力的计算

钢筋切断机切断过程分析及最大冲切力的计算太原重型机械学院机器厂高蕊随着建筑用钢筋强度的不断提高，对钢筋切断机切断能力的要求也越来越高。所谓钢筋切断机切断能力．就是利用飞轮惯性力通过传动系统作用给动定刀片以一定的冲切力，从而帮助电机克服钢筋峰值变形阻力...     

钢筋切断机最大切断力时曲柄转角的确定

钢筋切断机最大切断力时曲柄转角的确定高蕊（太原重机学院机器厂）最大切断力和此时的曲柄转角是设计钢筋切断机时计算电机功率和飞轮转动惯量的两个重要参数，准确地确定这两个参数的数值对于降低切断机的能耗系数与材耗系数，提高切断机的切断能力是很关键的。最大切断...     

钢筋切断机曲轴连杆机构的改进

钢筋切断机曲轴连杆机构的改进太原工业大学机器厂樊智慧我厂生产的ＧＱ４０Ｂ型钢筋切断机，其剪切运动是由一曲型的曲轴连杆机构完成的。但是由于切断机机体内脏狭小，在装配曲轴连杆时比较困难。尤其是在使用中发生故障需要维修时，拆卸曲轴连杆更加不易，给维修工作造...     

Distribution of organic contaminants in Lake Taihu

Water contamination in Lake Taihu and Lake Wulihu poses a threat to water supply and recreation. Water samples were collected during 1988–1989 for analysis of organic contaminants in the two lakes. Over 800 organic contaminants were detected by GC and GC-MS, and 84 of them were screened by a scoring system as priority contaminants. Results showed that the average concentration was one order of magnitude higher in Lake Wulihu than in Lake Taihu, although the number of contaminants in Lake Wulihu was only double those in Lake Taihu. Concentrations of phthalates, halohydrocarbons, and alkanes in Lake Taihu were close to those in Lake Wulihu, whereas the concentrations of alkylaromatics, anilines, phenols, alcohols, ketones, and polynuclear aromatics in Lake Taihu were lower than in Lake Wulihu by 2–3 orders of magnitude. The average concentration of contaminants in Lake Taihu reaches the highest during the rainy season while this occurs in Lake Wulihu during the dry season because of differences in water flow patterns in the lakes, conditions of the water environment, and physico-chemical properties of contaminants.     

不同介质中MOV小电流特性的对比研究

氧化锌电阻片(MOV)常用于过电压保护,其小电流特性决定了它的工频稳定性。随着电力技术的发展,MOV被应用于变压器绕组内部和超导电力系统中,MOV的工作介质为变压器油和液氮。将MOV在空气和变压器油、空气和液氮(77K)中分别进行对比试验,通过小波变换对原始数据进行去噪,利用各次谐波法提取阻性电流进行对比分析,结果显示:MOV在变压器油中的阻性电流峰值大于空气中的值,MOV在液氮中的晶界电容、阻性电流峰值均小于空气中的值。表明MOV的小电流特性在空气中优于变压器油中,在液氮温区优于常温下。     

Experimental copper and chromium deficiency and additional molybdenum supplementation in goats. II. Concentrations of trace and minor elements in liver, kidneys and ribs: haematology and clinical chemistry

Since the mid-1980s a previously undescribed disease has affected moose in south-western Sweden. Investigations made to reveal evidence of a viral aetiology have proved unsuccessful. Trace element studies in apparently healthy moose shot during regular hunting suggested a trace element imbalance, with excessive molybdenum uptake causing secondary copper deficiency. The results also indicated a possible chromium deficiency. To verify this hypothesis, an experimental study was performed in male goats fed a semi-synthetic diet for 1.5 years. The animals were kept and treated in four groups: Controls, Cu-deficient group (group 1), Cr-deficient group (group 2), and combined Cu- and Cr-deficient group with additional supplementation of tetrathiomolybdate for 10 weeks at the end of the study (group 3). The present paper presents tissue contents of trace and minor elements, haematology and clinical chemical parameters. Feed consumption and weight development, as well as pathological and histopathological investigations, were also performed in this study, but these results are presented elsewhere. Changes in trace element concentrations were determined by comparing groups 1, 2 and 3 with the control group. Increased concentrations were observed for Al, Ca, Co, Fe, Mo, Pb, Se in the liver; for Al, Cd, Co, Cr, Mo in the kidneys; and for Mn and Mo in the ribs. Considerable accumulation of Mn in ribs seems to be a useful way to determine oxidative stress. Decreases in Mg and P in all organs and blood serum is characteristic of Cu deficiency and molybdenosis. Also the ratio of Ca/Mg was increased as the result of tissue lesions causing an intracellular increase in Ca and decrease in Mg. The trace element changes observed in group 1 were enhanced by the Mo supplementation in group 3, resulting in characteristic patterns, 'spectra' of changes. The alterations were not as remarkable in group 2 as in the two other groups. However, Cr deficiency considerably influenced Al, Co, V and to a smaller extent also Mn in ribs. In groups 1 and 2, only a few minor changes were detected in the haematological parameters, probably caused by increased adrenal activity after transportation of the animals. In group 3, severe anaemia was present but also a leukopenia. For the different clinical chemical parameters measured, all three groups showed changes, explained mainly by the altered activity of enzymes induced by trace element deficiencies and imbalance. Impaired carbohydrate and lipid metabolism was seen in groups 1 and 3, with increased concentrations of glucose, lactate and triglycerides in serum. Increased concentrations of total bilirubin were measured in all three groups (bile stasis was also seen post mortem). A considerably increased concentration of serum urea was found in group 3, although there were no indications of renal insufficiency or dehydration. Regarding hormones, a substantial decrease was seen in thyroxine (T4) in group 3 as a result of the molybdenosis, but a minor decrease was also seen in group 1. Insulin on the other hand showed increased levels in group 3--and especially in group 2 due to the Cr deficiency but also affected by the molybdenosis. As could be expected, Cu deficiency (groups 1 and 3) caused low levels of caeruloplasmin, secondarily affecting the Fe metabolism in these animals. Protein abnormalities, detected as altered electrophoretic patterns of serum proteins, were also seen mainly in group 3. The findings were also confirmed by multivariate data analysis, where PCA revealed the overall impact of the deficiencies, and PLS regression coefficients indicated the influence on the various analytes.     

Editorial

Function analysis (FA) is considered to be at the core of value management (VM). However, research in the construction industry in the United States and Hong Kong indicates that this fundamental process is sometimes abbreviated or omitted from the VM process. In examining this situation in the Australian construction industry context, the research described in this paper aimed to gather a cross‐sectional view of the role of FA in VM in the Australian construction industry by means of a postal questionnaire survey. The results confirm that FA is not always used in the VM process in Australia. Moreover, the functional hierarchy is preferred to the function analysis systems techniques (FAST) diagram when FA is implemented. It is also found that the greater the knowledge the participants have of FA, the more likely FA would be used in the VM process; while the greater the difficulty in implementing FA, the lesser is the commitment to use FA. In addition it is found that, in many ways, the use of FA and VM in general in Australia mirrors that of its operation (difficulty in applying FA, lack of expert facilitators, etc.) in other countries around the world. Exceptions to this include the length of time VM has been used in Australia and the duration of the VM workshops, both of which are shorter than in most countries.     

动荡时代的都市空间愿景*#br# ——“大昆明计划”历史回溯#br#

1937年抗战全面爆发后,昆明以其对外交通枢纽的地位成为了抗战大后方重镇。随着抗战西迁来的人口、工业、金融业与建筑业在短时间内涌入昆明,这些要素加快了昆明城市的近代化进程,推动了新城市规划的产生。1939年民国《都市计划法》颁布后,昆明市工务局局长丁基实提出了“大昆明”设想,同年年底该局技士沈长泰根据设想绘制了“大昆明市设计草图”。至此,昆明市的规划及营建开始以建设大昆明市为指导,昆明未来城市发展的方向及定位就此确立。1940年,《昆明市政府中心工作计划书》颁布,其工务部分指出了建设大昆明市的几项系统性任务;1941年,在时任昆明市工务局局长唐英的主持下制定了《昆明市三年建设计划纲要》并在其中列出了城建的具体事项,同年云南省政府颁布《昆明市建筑规则》,对昆明市建筑设计及营建活动进行规范要求。至此,“大昆明计划”的理论演变成熟,并于1942年起开始实施。本文主要通过爬梳史料对“大昆明计划”的时代背景、演变过程、演变特征及其关联性进行考察,以求在复现历史的基础上探求“大昆明计划”的历史意义及影响。最后,笔者认为“大昆明计划”对近现代昆明市的城市格局产生了深远的影响,其应被视为近代昆明城市规划与城市空间转型的标志,而其规划思想在当下昆明的城市规划中仍有体现。     

Effects of sewage sludge on pH and plant availability of metals in oxidising sulphide mine tailings

A field study was conducted adjacent to the tailings deposit of the Aitik copper mine in the north of Sweden to investigate the effects of sewage sludge on pH and plant availability of Al, Mn, Cu, Zn, Ni, Pb, As, Cr and Cd in the oxidising sulphide tailings. One treatment was supplied with sewage sludge, while the control received NPK-fertiliser. The tailings samples were collected at the beginning and the end of the growing season and extracted by NH(4)NO(3), NH(4)Ac-EDTA and HNO(3). Plant tissue concentrations of the elements were determined in the above-ground parts of barley (Hordeum vulgare) and red fescue (Festuca rubra). The application of sewage sludge resulted in higher crop yields compared to the control, although the buffering capacity and the metal immobilising effect of the sludge were limited. The pH decreased from 6.6 to 4.3 in the control and from 6.4 to 4.8 in the sludge-treated tailings during the growing season, probably due to sulphide oxidation in the tailings. This resulted in increased levels of soluble elements in all treatments studied. Application of sewage sludge resulted in elevated levels of soluble Zn and lower values of soluble As and Cd in the unaltered tailings but increased levels of specifically adsorbed Cu, Ni and As in the oxidised tailings. This was partly reflected in the plants, as the application of sewage sludge resulted in 67 mg Zn kg(-1) in barley grains and 60 mg Zn kg(-1) in red fescue shoots, both values twice as high as the corresponding values in the control, but lower As contents in both straw (0.3 mg kg(-1)) and grain (0.06 mg kg(-1)) of barley compared to the control (0.6 and 0.2 mg kg(-1), respectively). In addition, red fescue grown in sludge-treated plots contained significantly higher levels of Al, Cu, Pb, As and Cr compared to the control. The levels of several metals in barley and red fescue grown in both treatments exceeded background values found in the literature. The Cu content in barley straw exceeded 100 mg kg(-1) in both treatments and might be toxic to grazing animals. Thus, this study suggests that adding sewage sludge to the mine tailings at Aitik would not counteract the effects of the sulphide oxidation in the tailings. Furthermore, using a sequential extraction technique proved preferable to using total metal analysis in order to predict plant uptake of the elements in the tailings.     

Alteration of arsenopyrite in soils under different vegetation covers

The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krušné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO₄·2H₂O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments.     

Discourses of Infrastructure and Citizenship in Post-Apartheid Soweto

In this article, I locate Soweto at the epicentre of the changing relationship between state infrastructural capacity on the one hand, and imaginations of citizenship on the other. Far from the ??hidden?? or merely technical functioning of urban governance, infrastructure has always been central to the urban politics and everyday life of townships in South Africa. The infrastructural capacity of the apartheid state entrenched the segregated apartheid urban system, and was simultaneously the target of political protest in the 1980s. Infrastructure plays a significant role in political expectations in post-apartheid South Africa. Through policies such as the Reconstruction and Development Program and Developmental Local Government, the post-apartheid state has attempted to re-frame citizenship of South Africans, especially in townships, through the provision of housing and basic services. The emergence, therefore, of service delivery protests in townships and informal settlements in the early 2000s marked the possible limits of a post-apartheid citizenship. Based on field research conducted in Soweto in the mid 2000s, and a number of follow-up interviews in 2010 and 2011, I trace the shifting relationship between infrastructure and citizenship as it emerges in the everyday life of contemporary Soweto. I show how electricity disconnections by the municipality and state electricity utility Eskom in the early 2000s??and the subsequent protests they sparked??provided the context for challenging the limits of post-apartheid citizenship. Residents of Soweto were able to link the ??hidden?? infrastructure of electricity cables and wires to a particular narrative of place. Returning to Soweto in 2010, in the midst of protest action against water prepaid metres in Phiri neighbourhood, issues of access to basic services, housing evictions and unemployment still characterise the everyday life of Soweto. As with protests against electricity disconnections, protests against water prepaid metres have linked urban infrastructure to articulations of citizenship that reside in particular narratives of place. But so too do newer forms of ??consumer citizenship??, particularly in the form of a new shopping mall that was opened in 2008, and which stands in stark contrast to the politics of basic services.     

生态还是自然主义: 关于当代种植设计的简要回顾和一些思考

Nature is a cultural construct, and a symbolic form to our cultural landscape. It plays a critical role in the profession of Landscape Architecture, shaping both the practice in the constructed environment as well as the conception of landscape in Pedagogy. This article evaluates contemporary landscape architecture practice in the U.S. through the lens of planting design and ecological design approaches. This retrospect situates selected individuals and their practices in the field of landscape architecture in the past two decades, in parallel with the evolving ecological understanding. These individuals and their works demonstrate the changes in planting design and ecological thinking in the professional practice, and most importantly how these changes contribute to current ecological design methodologies, landscape aesthetics, and public perception of landscape. In addition, the article aims to illustrate a shifting conception of Nature over time and in different cultural context, in which different conceptions of Nature facilitate various approaches to addressing environmental issues. By situating in such context, the article hopes to provide a critical view of contemporary American landscape architecture practice and the current ecological agenda, in order to enable discussions regarding the professional practice in the future.