Correlating Multiple 2D Vision Trackers for 3D Object Tracking on Construction Sites

Tracking methods have the potential to retrieve the spatial location of project related entities such as personnel and equipment at construction sites, which can facilitate several construction management tasks. Existing tracking methods are mainly based on Radio Frequency (RF) technologies and thus require manual deployment of tags. On construction sites with numerous entities, tags installation, maintenance and decommissioning become an issue since it increases the cost and time needed to implement these tracking methods. To address these limitations, this paper proposes an alternate 3D tracking method based on vision. It operates by tracking the designated object in 2D video frames and correlating the tracking results from multiple pre-calibrated views using epipolar geometry. The methodology presented in this paper has been implemented and tested on videos taken in controlled experimental conditions. Results are compared with the actual 3D positions to validate its performance.

Testing of Depth-Encoded Hough Voting for Infrastructure Object Detection

The lack of viable methods to map and label existing infrastructure is one of the engineering grand challenges for the 21st century. For instance, over two thirds of the effort needed to geometrically model even simple infrastructure is spent on manually converting a cloud of points to a 3D model. The result is that few facilities today have a complete record of as-built information and that as-built models are not produced for the vast majority of new construction and retrofit projects. This leads to rework and design changes that can cost up to 10% of the installed costs. Automatically detecting building components could address this challenge. However, existing methods for detecting building components are not view and scale-invariant, or have only been validated in restricted scenarios that require a priori knowledge without considering occlusions. This leads to their constrained applicability in complex civil infrastructure scenes. In this paper, we test a pose-invariant method of labeling existing infrastructure. This method simultaneously detects objects and estimates their poses. It takes advantage of a recent novel formulation for object detection and customizes it to generic civil infrastructure scenes. Our preliminary experiments demonstrate that this method achieves convincing recognition results.

Climate resilience of schools: a case study

Social and political concerns are frequently reflected in the design of school buildings, often in turn leading to the development of technical innovations. One example is a recurrent concern about the physical health of the nation, which has at several points over the last century prompted new design approaches to natural light and ventilation. The most critical concern of the current era is the global, rather than the indoor, environment. The resultant political focus on mitigating climate change has resulted in new regulations, and in turn considerable technical changes in building design and construction. The vanguard of this movement has again been in school buildings, set the highest targets for reducing operational carbon by the previous Government. The current austerity measures have moved the focus to the refurbishment and retrofit of existing buildings, in order to bring them up to the exacting new standards. Meanwhile there is little doubt that climate change is happening already, and that the impacts will be considerable. Climate scientists have increasing confidence in their predictions for the future; if today’s buildings are to be resilient to these changes, building designers will need to understand and design for the predicted climates in order to continue to provide comfortable and healthy spaces through the lifetimes of the buildings. This paper describes the decision processes, and the planned design measures, for adapting an existing school for future climates. The project is at St Faith’s School in Cambridge, and focuses on three separate buildings: a large Victorian block built as a substantial domestic dwelling in 1885, a smaller single storey 1970s block with a new extension, and an as-yet unbuilt single storey block designed to passivhaus principles and using environmentally friendly materials. The implications of climate change have been considered for the three particular issues of comfort, construction, and water, as set out in the report on Design for Future Climate: opportunities for adaptation in the built environment (Gething, 2010). The adaptation designs aim to ensure each of the three very different buildings remains fit for purpose throughout the 21st century, continuing to provide a healthy environment for the children. A forth issue, the reduction of carbon and the mitigation of other negative environmental impacts of the construction work, is also a fundamental aim for the school and the project team. Detailed modelling of both the operational and embodied energy and carbon of the design options is therefore being carried out, in order that the whole life carbon costs of the adaptation design options may be minimised. The project has been funded by the Technology Strategy Board as part of the Design for Future Climates programme; the interdisciplinary team includes the designers working on the current school building projects and the school bursar, supported by researchers from the University of Cambridge Centre for Sustainable Development. It is hoped that lessons from the design process, as well as the solutions themselves, will be transferable to other buildings in similar climatic regions.

The steel scrap age.

Steel production accounts for 25% of industrial carbon emissions. Long-term forecasts of steel demand and scrap supply are needed to develop strategies for how the steel industry could respond to industrialization and urbanization in the developing world while simultaneously reducing its environmental impact, and in particular, its carbon footprint. We developed a dynamic stock model to estimate future final demand for steel and the available scrap for 10 world regions. Based on evidence from developed countries, we assumed that per capita in-use stocks will saturate eventually. We determined the response of the entire steel cycle to stock saturation, in particular the future split between primary and secondary steel production. During the 21st century, steel demand may peak in the developed world, China, the Middle East, Latin America, and India. As China completes its industrialization, global primary steel production may peak between 2020 and 2030 and decline thereafter. We developed a capacity model to show how extensive trade of finished steel could prolong the lifetime of the Chinese steelmaking assets. Secondary steel production will more than double by 2050, and it may surpass primary production between 2050 and 2060: the late 21st century can become the steel scrap age.

Biobjective optimisation of preliminary aircraft trajectories

The protection of the environment against pollutants produced by aviation is of great concern in the 21st century. Among the multiplicity of proposed solutions, modifying flight profiles for existing aircraft is a promising approach. The aim is to deliver and understand the trade-off between environmental impact and operating costs. This work will illustrate the optimisation process of aircraft trajectories by minimising fuel consumption and flight time for the climb phase of an aircraft that belongs to A320 category. To achieve this purpose a new variant of a multi-objective Tabu Search optimiser was evolved and integrated within a computational framework, called GATAC, that simulates flight profiles based on altitude and speed. © 2013 Springer-Verlag.

Progress of Si-based nanocrystalline luminescent materials

Si-based nanomaterials are some new photoeletronic and informational materials developed rapidly in recent years, and they have potential applications in the light emitting devices, e. g. Si light emitting diode, Si laser and integrated Si-based photoelectronics. Among them are nano-scale porous silicon (ps), Si nanocrystalline embedded SiO2 (SiOx, x < 2.0) matrices, Si nanoquantum dot and Si/SiO2 superlattice, etc. At present, there are various indications that if these materials can achieve efficient and stable luminescence, which are photoluminescence (PL) and electroluminescence (EL), it is possible for them to lead to a new informational revolution in the early days of the 21st century. In this article, we will mainly review the progress of study on Si-based nanomaterials in the past ten years. The involved contents are the fabricated methods, structural characterizations and light emitting properties. Finally, we predicate the developed tendency of this field in the following ten years.

Eigenmode confinement in semiconductor microcavity lasers with an equilateral triangle resonator

We analyze the mode behaviors for semiconductor lasers with an equilateral triangle resonator by deriving the mode field distribution and the eigenvalue equation. The eigenvalue equation shows that the longitudinal mode wavelength interval is equivalent to that of a Fabry-Perot cavity with the cavity length of 1.5a, where a is the side length of the equilateral triangle resonator. The transverse waveguiding is equivalent to as a strip waveguide with the width of root 3a/ 2, and the number of transverse modes supported by the resonator is limited by the total reflection condition on the sides of the equilateral triangle. Semiconductor microcavity laser with an equilateral triangle resonator is suitable to realize single mode operation, and the mode wavelength can be adjusted by changing the side length.

Photoluminescence characteristics of GaAs/AlGaAs quantum dot arrays fabricated by dry and dry-wet etching

GaAs/AlGaAs quantum dot arrays with different dot sizes made by different fabrication processes were studied in this work. In comparison with the reference quantum well, photoluminescence (PL) spectra from the samples at low temperature have demonstrated that PL peak positions shift to higher energy side due to quantization confinement effects and the blue-shift increases with decreasing dot size, PL linewidths are broadened and intensities are much reduced. It is also found that wet chemical etching after reactive ion etching can improve optical properties of the quantum dot arrays.

Normal-incident SiGe/Si MQWs photodetectors operating at 1.3 mu m

A normal-incident SiGe/Si multiple quantum wells (MQWs) photodetector was reported. The structure and fabrication process of the photodetector were introduced. The photocurrent spectra measurement showed that the response spectra was expanded to 1.3 mu m wavelength. The quantum efficiency of the photodetector was 0.1% at 1.3 mu m and 20% at 0.95 mu m.

650nm AlGaInP quantum well lasers for the application of DVD

Main application of 650nm band laser diodes are for digital versatile disk (DVD). We demonstrate here the 650nm AlGaInP LD grown by LP-MOCVD with the structure of selected buried ridge waveguide. Excellent performance of LD have been achieved such as threshold current, threshold current density as low as 20mA and 350A/cm(2) respectively at room temperature, the operating temperature up to 90 for the linear power output of 5mw. RIN is about -130db/Hz, The samples of LD have been certified by PUH manufacturers.

21世纪中国粮食生产布局构思

为满足 2 1世纪中国对粮食的需求 ,提出“发展东部 ,提高中部 ,开发西部”的粮食生产战略布局 ,就是在东部平原区发展产业化粮食生产 ,使之成为中国优质商品粮食主要生产基地 ;在中部高原区要大力治理水土流失 ,提高粮食生产的环境质量 ,从而提高粮食产量水平 ;在西部高寒及荒漠区要充分开发光能、土、水资源优势 ,进一步开发高寒农业与绿洲农业的粮食生产潜力

中国21世纪水土保持工作的思考

水土资源是人类生存的基本资源 ,是国民经济持续发展的基础。按照国家生态环境建设规划要求 ,2 1世纪水土保持工作任务繁重而艰巨。 2 1世纪水土保持的特点是内涵不断扩充 ,综合性日益突出 ,大量运用高新技术 ,产业进一步发展。建议提高水土流失治理的科技含量 ,培养和建立一支高水平、高素质的水土保持队伍 ,引进新的监测技术与管理手段 ,建立一批高水平的综合治理试验示范工程和基地

中国城市建设与地质灾害之分析与对策

在大量调查、分析与研究的基础上 ,结合中国经济发展中城市快速发展面临的一系列地质灾害 ,采用自然科学与社会科学相互交叉的方法 ,分析了城市地质灾害的危害性及对城市发展的影响 ,根据中国城市发展的实际情况和 2 0 0 1年以后的远景目标 ,因地制宜地提出了整治城市灾害的基本对策与管理措施 ,为国家制定城市发展远景规划和奋斗目标提供基本思路