机器人登陆月球建造建筑——轮廓工艺的潜力

美国南加利福尼亚大学的比洛克·霍什内维斯(Behrokh Khoshnevis)教授发明的轮廓工艺(contour crafting)是一种由数字控制的建造工艺,通过分层制造技术,可以直接按照计算机模型制造部件。由于无需使用传统混凝土施工中的模板,轮廓工艺可以大大降低成本和建造时间。通过机器人进行建造,最大限度地减少了劳动力的消耗,使该技术凸显巨大的潜力,尤其是在相对危险的环境中,比如充满对人体极具损害的高度辐射的月球。目前,由美国宇航局资助的研究正在探索使用轮廓工艺在月球上建造建筑的潜力,建造所需材料来自月球表面丰厚的风化层。本文对该项研究进行介绍,并对在月球上使用轮廓工艺的优势进行评估。     

An Aggregate Production Planning Model Incorporating Dynamic Productivity: Part I. Model Development

All aggregate planning models, except two, utilize a constant productivity factor throughout the planning horizon. The two models which allow changing productivity factors have limitations and unrealistic assumptions. This article incorporates into an aggregate planning model the effects of manpower-level transactions on productivity.     

An Aggregate Production Planning Model Incorporating Dynamic Productivity: Part II. Solution Methodology and Analysis

In Part I in a previous issue, the authors developed a procedure for incorporating dynamic productivity considerations into aggregate planning models. However, the dynamic cost functions of these models result in heterogeneous decision systems which are difficult to solve. In this article a solution methodology is discussed that was developed for dynamic aggregate planning models. In addition, the results from using a dynamic productivity aggregate planning model are analyzed. It is concluded that dynamic productivity can be significant; incorporating these considerations into a model can provide more realistic results.     

A heuristic to capture multi-directional lateral tactile perception

Multi-directional tactile perception adds significant complexity when interpreting haptic experimental data. In perceiving tactile stimulus direction, we often observe a lack of one-to-one stimulus-response compatibility, mostly due to confounding sensations that reinforce and/or distort a primary stimulus. This study presents the development of a metric to capture multi-directional lateral tactile perception on a finger pad. Sixty-two subjects rated the direction and magnitude of lateral motion from a single probe moving in one of the eight possible directions. A heuristic based on a vector matrix was developed to capture and integrate the relative contribution of each subject's rated directional perception in x–y coordinates. This article explains the theoretical underpinnings and the justifications for this heuristic and highlights the usefulness of this approach for future haptic system designs.     

Advancements in the selective inhibition sintering process development

Selective inhibition sintering (SIS) is a new layer-based rapid prototyping process that fabricates parts by joining polymer powder particles in the part's body to form a coherent solid and by preventing particles from joining at the part's boundary to form edges. This paper presents the fundamentals of the SIS process, its dedicated path generator, material selection research and the application of response surface methodology which has led to optimum performance, given various factors affecting part strength, surface quality and dimensional accuracy.     

Centralized sensing and control of multiple mobile robots

We discuss the development ideas and merits of a single centralized station to provide supervision, sensing, control, intelligence and perhaps power to a colony of robots, organized for the performance of specific tasks. The consequence of such an approach is that each robot can be much simpler, smaller and less expensive, since no on-board sensing, control and intelligence are required. The issues to be studied concern tradeoffs in control (bandwidth, accuracy, channel capacity); relations between numbers of controllable robots and task suitability and representation for control.     

Design and analysis of a thermal hydraulic integral test facility for Bushehr nuclear power plant

In this paper, design and analysis of a thermal hydraulic integral test facility for Bushehr Nuclear Power Plant (NPP) is presented. The Bushehr Integral Test Facility (BITF) is a test facility designed to model the thermal-hydraulic behaviours of the Bushehr NPP (VVER-1000) pressurized water reactors currently in use in IRAN. These reactors have unique features that differ from other PWR designs. The BITF simulates the major components and systems of the reference NPP, making it possible to examine postulated small and medium break a loss of coolant accidents (LOCAs) and operational transients. The BITF is a volume-scaled model (1:1375). To ensure that gravitational forces remain equal to those in the reference reactor, the major components and systems in the BITF preserve 1:1 elevation equivalence to the reference reactor. The facility has four loops (each one consists of a hot leg, a steam generator, a loop seal, a main circulation pump and a cold leg), a pressurizer connected via two surge line to the hot leg of the loops 2, 4, the emergency-core-cooling system (ECCS) which is provided by an active pump simulating high and low pressure injection systems, and four hydro-accumulators. The report also contains a comparison between experimental data of PSB test facility and RELAP5 calculations of BITF facility under steady state condition of the reactor power 15% from the nominal.     

The effect of renewable energy and urbanization on CO2 emissions: A panel data

Europe has experienced fast-paced urbanization development over the past three decades. This paper empirically investigates the long-run equilibrium relationships and causal relationships among urbanization, renewable energy consumption, and CO₂ emissions, and this is important for EU countries’ future sustainable development. DOLS and FMOLS approaches are used for the period 1992–2014 .

Granger causality results show that there is a unidirectional relationship from CO₂ emissions to urbanization, and there is no causality between renewable energy consumption and CO₂ emissions. The results have important implications for EU policymakers on the path toward a sustainable society. Urbanization can have negative impacts on the natural environment with the net effect being hard in EU countries.