NASA has developed an experimental flight payload (referred to as the Space Communication and Navigation (SCAN) Test Bed) to investigate software defined radio (SDR) communications, networking, and navigation technologies, operationally in the space environment. The payload consists of three software defined radios each compliant to NASAs Space Telecommunications Radio System Architecture, a common software interface description standard for software defined radios. The software defined radios are new technology developments underway by NASA and industry partners launched in 2012. The payload is externally mounted to the International Space Station truss to conduct experiments representative of future mission capability. Experiment operations include in-flight reconfiguration of the SDR waveform functions and payload networking software. The flight system will communicate with NASAs orbiting satellite relay network, the Tracking and Data Relay Satellite System at both S-band and Ka-band and to any Earth-based compatible S-band ground station. The system is available for experiments by industry, academia, and other government agencies to participate in the SDR technology assessments and standards advancements.

关键词：空间通信；通信卫星；无线电通信；试验台；无线电设备

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In disadvantaged grids, communication resources are scarce and variable. Thus, it is important that middleware and applications are able to adapt to the available capacity. This means that knowledge of the networking environment the C2 software is operating in is of great importance. Monitoring of networks carrying data is important in improving quality of service. There are two main types of monitoring: monitoring in the planning phase (i.e., testing that the maximum achievable throughput is in accordance with the agreement); and monitoring during deployment (i.e., when the network is actually being used). Here, it is important to know the current load (e.g., link utilization) to be able to shape and control data traffic in a coherent manner. There exist many solutions capable of doing this, but they are mostly geared towards use on the Internet and in corporate networks. Sending data to and from mobile units, like military vehicles moving in a combat zone, provides challenges that may make some current tools unsuitable. In this paper, we focus on freely available tools, and attempt to identify which tools are suitable for the planning phase and which are suitable for the deployment phase in disadvantaged grids.

关键词：可用性；带宽；指挥和控制系统；通信网络；通信交通

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In the United States Environmental Protection Agency's (USEPA) current pesticide risk assessment process, a pair of laboratory avian reproduction tests with mallards (Anas platyrhynchos) and northern bobwhites (Colinus virginianus) is conducted to evaluate how dietary pesticide exposure affects a standard suite of reproduction endpoints (USEPA 1996). The results of these tests are used in calculating risk quotients (RQ) by comparing the reported no-observed-adverse-effect concentration (NOAEC) for the most sensitive measured endpoint(s) with estimates of the maximum dietary exposure expected for a given application rate. As a screening tool, RQs are compared to an established regulatory level-of-concern to categorize the potential for unacceptable risk. Because of the high degree of uncertainty in these simple tools for characterizing risk, RQs typically incorporate conservative or worst-case assumptions about exposure and toxicity to reduce the chances of concluding a chemical has an acceptable level of risk when in fact it does not (i.e., false negative conclusion). Consequently, risk quotients can be used to identify the environmental concentration above which adverse effects to avian reproduction may occur, but they cannot determine the probability or magnitude of potential reproductive effects.

关键词：农药；马尔可夫链；巢生产力模型；技术手册；风险评估

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Theoretical studies of the possibility of forming ammonia electrochemically at ambient temperature and pressure are presented. Density functional theory calculations were used in combination with the computational standard hydrogen electrode to calculate the free energy profile for the reduction of N2 admolecules and N adatoms on several close-packed and stepped transition metal surfaces in contact with an acidic electrolyte. Trends in the catalytic activity were calculated for a range of transition metal surfaces and applied potentials under the assumption that the activation energy barrier scales with the free energy difference in each elementary step. The most active surfaces, on top of the volcano diagrams, are Mo, Fe, Rh, and Ru, but hydrogen gas formation will be a competing reaction reducing the faradaic efficiency for ammonia production. Since the early transition metal surfaces such as Sc, Y, Ti, and Zr bind N-adatoms more strongly than H-adatoms, a significant production of ammonia compared with hydrogen gas can be expected on those metal electrodes when a bias of - 1 V to - 1.5 V vs. SHE is applied. Defect-free surfaces of the early transition metals are catalytically more active than their stepped counterparts.

关键词：制氢；N-2过渡金属；电催化剂；理论评价

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Oak Ridge National Laboratory has been investigating a new class of Fe-based amorphous material stemming from a DARPA, Defense Advanced Research Projects Agency initiative in structural amorphous metals. Further engineering of the original SAM materials such as chemistry modifications and manufacturing processes, has led to the development of a class of Fe based amorphous materials that upon processing, devitrify into a nearly homogeneous distribution of nano sized complex metal carbides and borides. The powder material is produced through the gas atomization process and subsequently utilized by several methods; laser fusing as a coating to existing components or bulk consolidated into new components through various powder metallurgy techniques (vacuum hot pressing, Dynaforge, and hot isostatic pressing). The unique fine scale distribution of microstructural features yields a material with high hardness and wear resistance compared to material produced through conventional processing techniques such as casting while maintaining adequate fracture toughness. Several compositions have been examined including those specifically designed for high hardness and wear resistance and a composition specifically tailored to devitrify into an austenitic matrix (similar to a stainless steel) which poses improved corrosion behavior.

关键词：钢铁；不锈钢；粉末冶金；非晶材料

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Directly-generated compressive residual stress has become a widely used surface modification technique. Intentional residual stress in solid materials can be produced by different surface compression methods. It is well known how residual stress field is influenced by the parameters of the shoot peening but only few articles address the phenomenon about the evolution of the stress during the operation of the machine component. The literature on residual stress decrease caused by fatigue load is scarce and the kinetics of this mechanism is not yet investigated. The present work reports on the examination of the effect of the fatigue load on compressive residual stress strengthened specimens. Investigations have been conducted at three stress levels. Residual stress data have been measured by X ray diffraction method before fatigue load and measurements have been repeated after defined fatigue cycles.

关键词：钢铁；残余应力；X射线衍射仪；疲劳

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An experimental campaign was undertaken at the Von Karman Institute, Belgium, aimed at investigating the sliding doors inlet starting mechanism for a hypersonic scramjet inlet. This campaign provides the first step upon a much larger inlet starting investigation, with the results providing a backbone for comparison to future 2D and 3D transient RANS numerical studies. A scaled 2D representation of the SCRAMSPACE-I geometry was constructed, with two steel 3.2mm thick doors extending upstream from the inlet leading edge at an angle of 20 degrees. After achieving steady flow conditions, the doors were then retracted via a pneumatic piston and cabling system, with the resulting flow phenomena captured via visualization as well as quantitative instrumentation. The test campaign was undertaken in the H3 Wind Tunnel Facility, which provided a jet at Mach 6 at various reservoir pressures, with variance in Reynolds number used to simulate changing altitude conditions. Due to limitations with regards to tunnel blockage and diffuser placement, a scaling factor of 5.1 was applied to the model geometry proportionally in both the x and y directions. Successful inlet starting was achieved at conditions simulating flight at an altitude of approximately 29 km. Schlieren visualization techniques were employed, showing that supersonic conditions were indeed obtained in the inlet for approximately 32 flow lengths. Senflex thin film arrays, located on the inner surfaces of the inlet, captured the transient heat flux progression at different locations along the inlet. These profiles accurately captured the phenomena observed via the Schlieren imaging, in particular the propagation of shock structures into the inlet during the inlet starting procedure. Stanton number distributions along both arrays were extracted and showed a close comparison to those expected from numerical simulations reconstructed test flow conditions, which lends credibility to the integrity of the heat flux results.

关键词：钢铁；冲压发动机进气口；空气呼吸引擎

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The number of control loops used in process industry is growing continuously, whilst manpower is being reduced. Consequently even companies that have embraced new control technologies struggle to maintain satisfactory performance over the long term. Numerous investigations have shown that the performance of control systems in the process industries is not satisfactory, as mentioned in Chap. 1. This particularly applies for the steel industry, where it is the norm to perform controller tuning only at the commissioning stage and then never again. A loop that worked well at one time is prone to degradation over time unless regular check and maintenance is undertaken.

关键词：钢铁；回路；控制系统；调试

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This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory experiments. Tests were done using a vacuum roller rig for a range of roller misalignment angles. The wear in these tests was mainly adhesive wear. The measured wear rates were highly correlated to the misalignment angle. For all tests with some roller misalignment, the steel rollers lost mass while the titanium rollers gained mass indicating strong adhesion of the steel with the titanium alloy. Inspection of the rollers revealed that the adhesive wear was a two-way process as titanium alloy was found on the steel rollers and vice versa. The qualification test unit made use of 440F steel rollers in the annealed condition. Both annealed 440F steel rollers and hardened 440C rollers were tested in the vacuum roller rig to investigate possibility to reduce wear rates and the risk of loose debris formation. The 440F and 440C rollers had differing wear behaviors with significantly lesser wear rates for the 440C. For the test condition of zero roller misalignment, the adhesive wear rates were very low, but still some loose debris was formed

关键词：合金;滚筒；钢；钛合金；钒合金

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Fine balance between active galvanic and passive barrier corrosion protection by zinc-rich hybrid paints is explored depending on the absolute and relative amounts of the electrically semi-conducting particles, viz. polypyrrole (PPy) modified alumina hydrate and multi-walled carbon nanotubes (MWCNTs) and the zinc pigments. The former was varied between 3.21 and 1.75 wt., the latter was altered from 70 to 80 wt.in the primers. The coating with less zinc indicated firm and stable barrier nature in a 254 h immersion test whereas the primer with greater zinc content afforded superior galvanic corrosion prevention in salt-mist test over 142 days. Different nature of the coatings are expounded on the basis of structure and 3D arrangement of the nano-size inhibitor particles in the epoxy vehicle besides interpreted considering varied grain contents caused changing electrical percolation and electrolytic conductivity of the primers.

关键词：钢铁;纳米管;低碳钢;富锌涂料

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