摘要：An open path atmospheric composition monitor is designed based on ultraviolet differential absorption *** current correction and diode response correction are used to improve the detection limit and Savitzky-Golay filter is used to improve the measurement *** experimental results show that the designed system has the ability to measure NO and NO 2 in real time with reasonable *** detection limit of the system is about 0.25 ppm for NO and 0.28 ppm for NO 2 .When the concentration level of the target gases is below 100 ppm,the system has good linearity and high measurement accuracy,i.e.,the measurement accuracy is about 2%for NO and about 4%for NO 2 .The detection limit of dark current can be improved by about 5 to 10 ppb,and the correction of diode response can improve the detection limit by around 30 *** window average can improve the detection limit at low concentration levels but will generate more errors at higher concentration ***,the designed system meets the requirement of measuring multi-species air pollutants in real time and accurately.

摘要：Light-weighting involves the use of advanced materials and engineering methods to enable structural elements to deliver the same,or enhanced,technical performance while using less *** concept has been extensively explored and utilised in many industries from automotive applications to fashion and packaging and offers significant potential in the aviation *** implementations of light-weighting have involved use of high performance materials such as composites and optimisation of structures using computational aided engineering approaches with production enabled by advanced manufacturing methods such as additive manufacture,foam metals and hot *** paper reviews the principal approaches used in light-weighting,along with the scope for application of light-weighting in aviation applications from power-plants to airframe components.A particular area identified as warranting attention and amenable to the use of lightweighting approaches is the design of solar powered aircraft *** high aspect ratio typically used for these can be associated with insufficient stiffness,giving rise to non-linear deformation,aileron reversal,flutter and rigid-elastic *** applications considered include ultralight aviation components and sub-systems,UAVs,and *** optimisation approaches can be applied to optimise the layout of structural elements,as well as geometrical parameters in order to maximise structural stiffness,minimise mass and enable incorporation of energy storage *** use of additive manufacturing technologies,some capable of producing composite or multi-material components is an enabler for light-weighting,as features formally associated with one principal function can be designed to fulfil multiple functionalities。

摘要：The gas turbine engine internal air system provides cooling and sealing air to a series of critical subsystems and components such as high pressure gas turbine blades,as well as controlling the thrust load on the turbine and compressor spool *** potential variations for the internal air system are possible,depending on the requirement,expertise and command of intellectual *** subsystems,such as rim seals,pre-swirl systems,and rotating cavities have been the subject of extensive development and analysis leading to robust design *** there remains scope for further consideration of the overall system design,and this paper explores the use of a decision analysis tool called morphological analysis applied to the internal air *** analysis provides an effective means for tackling issues where there is uncertainty,as is the case with many design scenarios,including the internal air system,with some specific parameters and information not available until later in the design phase,after the key geometry has been *** problem space comprising seven principal parameters,and a cross consistency matrix which allows identification of compatible and incompatible states are presented.

摘要：Broad-host-range synthetic biology is an emerging frontier that aims to expand our current engineerable domain of microbial hosts for biodesign *** more novel species are brought to“model status,”synthetic biologists are discovering that identically engineered genetic circuits can exhibit different performances depending on the organism it operates within,an observation referred to as the“chassis effect.”It remains a major challenge to uncover which genome-encoded and biological determinants will underpin chassis effects that govern the performance of engineered genetic *** this study,we compared model and novel bacterial hosts to ask whether phylogenomic relatedness or similarity in host physiology is a better predictor of genetic circuit *** was accomplished using a comparative framework based on multivariate statistical approaches to systematically demonstrate the chassis effect and characterize the performance dynamics of a genetic inverter circuit operating within 6 *** results solidify the notion that genetic devices are strongly impacted by the host ***,we formally determined that hosts exhibiting more similar metrics of growth and molecular physiology also exhibit more similar performance of the genetic inverter,indicating that specific bacterial physiology underpins measurable chassis *** result of this study contributes to the field of broad-host-range synthetic biology by lending increased predictive power to the implementation of genetic devices in less-established microbial hosts.

摘要：Solid oxide fuel cell(SOFC) vehicles are considered to have broad prospects for development, and the high operating temperature of SOFC results in great potential for waste-heat recovery. Many concepts for utilizing waste heat of SOFC have been suggested and studied, and most of them directly couple an SOFC to a gas turbine, which require the SOFC to operate at an elevated pressure and make the system less flexible and thus harder to operate. In recent years, with the development of turbine and heat exchanger technology, the supercritical carbon dioxide(S-CO_2) power cycle has raised widespread attractions for the waste recovery. This study explores the potential of S-CO_2 Brayton cycle to realize waste-heat recovery for an SOFC vehicle. The SOFC can operate at atmospheric pressure, and the hybrid system is easier to operate than the directly coupled systems. In this paper, a simple recuperated S-CO_2 Brayton cycle is proposed and the key component, radial inflow turbine is designed and focused. The flow state of the designed turbine is analyzed in detail based on computational fluid dynamics(CFD) numerical simulation. Five cases with different impeller tip clearances are numerically simulated to study its influence on the turbine performance. In addition, off-design performance analysis of the radial inflow turbine is conducted considering the temperature fluctuation of SOFC in practical applications.

摘要：本文基于作者于2014年5月在中国参观铁路建设成就时的一篇报告而写成。内容涵盖铁路发展历史简介,英国和中国铁路的对比,英国过去数十年间铁路提速情况的说明以及现有高速铁路的介绍。此外,本文还详细讨论了欧洲高铁的发展情况和铁路系统安全的分析比较,并对中国高铁的发展及英国高铁建设计划进行了说明。得出高速铁路系统在提高能量利用效率、增加旅客舒适度、控制碳排放量等方面有显著优势。

摘要：With projections indicating an increase in mobility over the next few decades andannual flight departures expected to rise to over 16 billion by 2050,there is a demand for theaviation industry and associated stakeholders to consider new forms of aircraft and *** requirements are recognized as a key driver in *** airline is the principalcustomer for the aircraft *** passenger is,in turn,the airline's principal customerbut they are just one of several stakeholders that include aviation authorities,airport operators,air-traffic control and security *** passenger experience is a key differentiator usedby airlines to attract and retain custom and the fuselage that defines the cabin envelope for thein-flight passenger experience and cabin design therefore receives significant attention for newaircraft,service updates and *** making in design is crucial to arrivingat viable and worthwhile cabin *** litle innovation will result in an aircraftmanufacturer and airlines using its products falling behind its *** much mayresult in an over-extension with,for example,use of immature technologies that do not havethe necessary reliability for a safety critical industry or sufficient value to justify the develop-ment *** multiple requirements associated with cabin design,can be viewed as an area for optimisation,accepting trade-offs between the various *** design,however,is often defined as developing a concept that resolves the contradictions and takes the solutiontowards a win-win *** our understanding and practice of design allows forbehaviors that enhance design thinking through divergence and convergence,the use ofabductive reasoning,experimentation and systems *** paper explores and definesthe challenges of designing the aireraft cabin of the future that will deliver on the multiplerequirements using experiences from the A350 XWB and future cabin design

摘要：In order to achieve holistic urban plans incorporating transport infrastructure,public space and the behavior of people in these spaces,integration of urban design and computer modeling is a promising way to provide both qualitative and quantitative support to *** paper describes a systematic literature review following a four-part ***,to understand the relationship of elements of transport,spaces,and humans,w e review policy and urban design strategies for promoting positive ***,we present an overview of the integration methods and strategies used in urban design and policy ***,metrics and approaches for evaluating the effectiveness of integrated plan alternatives are ***,this paper gives a review of state-of-the-art tools with a focus on seven com puter simulation *** article explores mechanisms underlying the complex system of transport,spaces,and humans from a multidisciplinary perspective to provide an integrated toolkit for designers,planners,modelers and decision-m akers with the current methods and their challenges.

摘要：Structural analysis of steel frames is typically performed using beam elements. Since these elements are unable to explicitly capture the local buckling behavior of steel cross-sections, traditional steel design specifications use the concept of cross-section classification to determine the extent to which the strength and deformation capacity of a cross-section are affected by local buckling. The use of plastic design methods are restricted to Class 1 cross-sections, which possess sufficient rotation capacity for plastic hinges to develop and a collapse mechanism to form. Local buckling prevents the development of plastic hinges with such rotation capacity for cross-sections of higher classes and, unless computationally demanding shell elements are used, elastic analysis is required. However, this article demonstrates that local buckling can be mimicked effectively in beam elements by incorporating the continuous strength method (CSM) strain limits into the analysis. Furthermore, by performing an advanced analysis that accounts for both geometric and material nonlinearities, no additional design checks are required. The positive influence of the strain hardening observed in stocky cross-sections can also be harnessed, provided a suitably accurate stress–strain relationship is adopted;a quad-linear material model for hot-rolled steels is described for this purpose. The CSM strain limits allow cross-sections of all slenderness to be analyzed in a consistent advanced analysis framework and to benefit from the appropriate level of load redistribution. The proposed approach is applied herein to individual members, continuous beams, and frames, and is shown to bring significant benefits in terms of accuracy and consistency over current steel design specifications.

摘要：As the demand for energy continues to increase, shale gas, as an unconventional source of methane(CH_4), shows great potential for commercialization. However, due to the ultra-low permeability of shale gas reservoirs, special procedures such as horizontal drilling, hydraulic fracturing, periodic well shut-in, and carbon dioxide(CO_2) injection may be required in order to boost gas production, maximize economic benefits, and ensure safe and environmentally sound operation. Although intensive research is devoted to this emerging technology, many researchers have studied shale gas design and operational decisions only in isolation. In fact, these decisions are highly interactive and should be considered simultaneously. Therefore, the research question addressed in this study includes interactions between design and operational decisions. In this paper, we first establish a full-physics model for a shale gas reservoir. Next, we conduct a sensitivity analysis of important design and operational decisions such as well length, well arrangement, number of fractures, fracture distance, CO_2 injection rate, and shut-in scheduling in order to gain in-depth insights into the complex behavior of shale gas networks. The results suggest that the case with the highest shale gas production may not necessarily be the most profitable design; and that drilling, fracturing, and CO_2 injection have great impacts on the economic viability of this technology. In particular, due to the high costs, enhanced gas recovery(EGR) using CO_2 does not appear to be commercially competitive, unless tax abatements or subsidies are available for CO_2 sequestration. It was also found that the interactions between design and operational decisions are significant and that these decisions should be optimized simultaneously.