Prediction of the sawing quality of Marmarit stones using the capability of artificial neural network

The sawing rate is one of the most significant and effective parameters in extracting building stones via diamond wire sawing. This parameter designates the capability of diamond wire sawing for sawing different stones; in addition, the parameter gives rise to economical considerations for quarry designers. In this study, the existent relations between stone geotechnical parameters and the sawing rate of stones via diamond wire sawing were analyzed using regression and correlation coefficient as well as the collected data from Marmarit stone quarries. Moreover, we estimated the sawing rate of Marmarit using the dimensional stone rock mass rating (DSRMR); upon comparison of the data obtained from DSRMR our pre‐collected data on quarries, we did not gain satisfactory results from DSRMR, hence we used artificial neural network (ANN). The results showed that the percentage of Silica, the coefficient of water absorption, the uniaxial compressive strength (UCS), and abrasive hardness are the proper parameters for creating the ANN. Discontinuities have the least effects possible on diamond wire sawing. Having given the training possibility of the ANN, and its ability to evaluate relations among input parameters, the ANN, which was being trained with Marmarit's traits, was an accurate network for estimating diamond wire sawing in Marmarit quarries, although it could not generalize this network for other stones such as Chini and Crystal. Copyright © 2011 John Wiley & Sons, Ltd.     

玻璃钢渔船总纵弯曲的实船试验研究

本文通过实船试验研究玻璃钢渔船的总纵弯曲,以求得玻璃钢渔船应变和挠度随载荷的变化特性,从而了解玻璃钢渔船的总纵强度。     

木板梳条机的研制

报导自制的用于制作细木制品坯料的自动化专用设备。其特点是生产效率高，加工面质量好。文中给出了该设备的主要结构和应用实例，并对主轴工作时的稳定性进行了分析．     

切磨过程中花岗石材料去除机理研究

深入理解切磨过程中花岗石材料的去除机理是优化加工设备，加工工具以及加工参数的基础。本文研究了花岗石的断口表面、锯切表面、粗磨表面以及精磨表面形貌特征，并结合切磨过程中临界载荷、单颗金刚石磨粒所承受的切削力以及比能特征，对加工表面形成机理进行了分析。研究表明，材料的去除机理与单颗磨粒的最大切削厚度直接相关。随着单颗金刚石磨粒最大切削厚度的减小、花岗石的去除方式也逐渐由脆性断裂为主转为塑性流变为主。由于不同的材料去除机制对应不同的能量消耗，可以通过调节单颗磨粒的最大切削厚度控制材料的去除方式，进而控制能量消耗。因此，均匀的磨粒出露高度对于控制切磨过程中材料的去除机理和优化加工过程具有重要意义。     

海洋测绘专业通科人才培养模式的探讨

在对国际海道测量师与海图制图师资格教育标准进行比较研究的基础上,提出了海洋测绘专业通科教育培养模式,并在教学内容与课程设置、实践教学环节、师资队伍知识结构与基本素质等有关方面进行了研究,同时分析了培养高素质海洋测绘人才在更新教学内容、教材图书资料建设和建立完善的教学保障体系方面需要解决的相关问题。     

Comparative assessment of water treatment using polymeric and inorganic coagulants

Portable water plays a vital role in improving human life, particularly in controlling the spread of diseases. However, problems associated with lack of potable water are still common especially in developing countries including Malawi. Until now little information exists on the effectiveness of available commercial coagulants used by national water boards in Malawi. Therefore, this study was undertaken in Southern Region Water Board (SRWB) to investigate the efficiency of polymeric coagulants (sufdfloc 3850 and algaefloc 19s) in turbidity reduction comparative with inorganic coagulant (aluminium sulphate) at Zomba, Liwonde, Mangochi, Chikwawa and Mulanje Treatment plants. The jar test method was used to determine the effectiveness of the water coagulants. The results revealed that sudfloc 3850 was most effective in reducing turbidity at Mangochi (99.4 ± 0.06%) and Liwonde (97.2 ± 0.04%) using 0.4 mg L⁻¹ flocculant dose. The Zomba, Mulanje and Chikwawa plants gave 19.56 ± 0.03%, 29.23 ± 0.02% and 9.43 ± 0.02% total reductions respectively. Algaefloc 19s afforded the highest turbidity reduction at Liwonde and Mangochi plants (98.66 ± 0.06 and 97.48 ± 0.05% at a dose of 0.4 and 0.6 mg L⁻¹ respectively), while Chikwawa provided the lowest (9.52 ± 0.01%). At the Zomba and Mulanje plants 20.5 ± 0.03% and 28.4 ± 0.04% reductions were obtained respectively. The inorganic flocculant, alum provided a 99.0 ± 0.05% and 98.6 ± 0.04% reduction at a dose of 4.0 mg L⁻¹ and 6.0 mg L⁻¹ at Zomba and Liwonde plants respectively. The lowest reductions in turbidity were achieved at Chikwawa (7.50 ± 0.01%), Mangochi (12.97 ± 0.02%) and Mulanje (25.00 ± 0.02). The best and optimum pH ranges for polymeric and inorganic coagulants were 7.20–7.80 and 7.35 to 7.57 respectively. The results further revealed that sudfloc 3850 and algaefloc 19s achieved faster formation of heavy flocs than alum. At 0.4 mg L⁻¹ flocculant dosage sudfloc 3850 and algaefloc 19s required ten times lower dosages than alum. Therefore, the polymeric coagulants could be used instead of alum, the choice dependant on the type of water.     

STATE PARKS AND JIM CROW IN THE DECADE BEFORE BROWN v. BOARD OF EDUCATION

African Americans had access to only a small number of state parks in the Jim Crow South. Between the end of World War II and the U.S. Supreme Court's 1954 Brown v. Board of Education decision, however, state park officials oversaw a relative expansion in the construction of facilities available to southern blacks. Emphasizing developments leading up to that landmark court ruling, I note that this trend did not indicate waning support for segregation among whites. Rather, this relative expansion was part of a strategy to protect Jim Crow by demonstrating that the “separate‐but‐equal” principle was being successfully achieved by southern park agencies. This intensified construction was largely a reaction to increasingly successful legal action in federal courts by the naacp generally; and officials in the state agencies hoped—unsuccessfully—to avoid challenges to state park segregation. After the Brown decision, several border states integrated their park systems, but most agencies displayed the reactionary defiance that characterized most white Southerners as the civil rights movement grew.     

Convergence or divergence?: Status and prospects for US climate strategy

The objective of this paper is to assess recent developments and prospects for future changes in United States (US) climate strategy. In doing so, the paper explores some of the key factors that have shaped strategies and policies to date, distinguishing between factors related to institutional and governance structures, linkages between science and policy, energy technology and the role of interest groups. Against this background, the paper attempts to explore future development paths for US climate policy. More specifically, the paper assesses opportunities for policy changes compared to the preferences of the current administration, and the prospects for future linkages between US and international climate change strategies. In brief, the paper argues that substantial changes are unlikely to take place in the near to medium term, leaving open, however, the possibility of wide-ranging changes in domestic politics or major incidents that could facilitate a shift in the perceived need for near-term action.     

锯切花岗石过程中金刚石承受载荷分析

通过检测锯切水平力、垂直力以及功率消耗，研究了花岗石据切过程中单颗粒承受的平均法向力持征，并探讨了节块中金刚石出露高度分布状态和锯切水槽对磨粒实际承受荷载的影响，研究结果对加工参数优化和金刚石工具设计具有参考价值。