Study of a Classical Strobe Composition

Many strobe compositions were discovered in the past but only a few have been studied and none of them were fully understood. This article aimed at introducing the ternary composition of ammonium perchlorate as oxidizer, magnalium as fuel, and barium sulfate as metal salt. Parameters that influence its performances are analyzed. First, the binary compositions ammonium perchlorate/magnesium and ammonium perchlorate/magnalium were studied to observe the differences in behavior by using magnalium instead of magnesium. Next, variations were applied to the ternary composition changing the fuel: oxidizer:metal salt ratio. Finally the effect of potassium dichromate was analyzed. It is often added to the composition because it is known to improve the regularity and sharpness of flashes. The burning behavior was recorded using a high speed camera, together with emission spectra using a Charged‐Coupled Device (CCD) camera coupled with a spectrometer and the temporal evolution of the intensity with a photodiode coupled with an oscilloscope. The results of the experiment give first insights into the physical and chemical mechanisms and give directions to the further study on strobe reactions.     

Measurement of Aerosol Organic Compounds Using a Novel Collection/Thermal-Desorption PTR-ITMS Instrument

We report the development and characterization of a proton-transfer-reaction ion trap mass spectrometer for the speciated measurement of organic compounds in atmospheric aerosols and show results from its first field deployment. The instrument uses an aerosol collection inlet to accumulate aerosol mass followed by rapid thermal desorption to volatilize the organic compounds for in situ analysis. We have performed laboratory studies to characterize instrument performance and the instrument was deployed aboard a NOAA research vessel during the Texas Air Quality Study 2006/Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS 2006/GoMACCS) in August–September 2006. The laboratory-determined detection limit for glutaric acid in mixed glutaric acid/NH ₄ HSO ₄ test aerosols was 0.22 ng collected mass, which corresponds to an estimated detection limit of 12 ng m^?3 for a 10 min sample based on the instrument sample flow rate of 1.8 L min^?1. During TexAQS 2006/GoMACCS, signals well above the detection limit were observed at a number of mass to charge ratios, mostly occurring during an extended period of active pollution photochemistry, but also including detection of possible primary emissions of aerosol-phase pyridine.     

iSatTV:支持交互式数字卫星电视应用的通信系统

交互电视需要一条回传通道以将数据从用户端发送到系统前端。有线电视公司采用有线电视系统作为回传通道；而直播系统运营商通常采用拨号或者手机网络等地面系统，这就不可避免地导致系统复杂化且价格昂贵。为解决通过卫星回传窄带数据的问题，Newtec开发出了该革命性的低成本解决方案以支持交互式电视服务。成本的降低是通过采用连续封装调制以及高效率信道编码技术而获得的。该系统名为iSatTV，遵循SATMODE技术规范，并刚成为新的欧洲标准。     

Six years children’s use of a neighbourhood

Journal of Housing and the Built Environment -     

Solving Satisfiability Problems Using Elliptic Approximations. A Note on Volumes and Weights

In this note we propose to use the volume of elliptic approximations of satisfiability problems as a measure for computing weighting coefficients of clauses of different lengths. For random 3-SAT formula it is confirmed experimentally that, when applied in a DPLL algorithm with a branching strategy that is based on the ellipsoids as well, the weight deduced yields better results than the weights that are used in previous studies.     

Water conflicts in tropical watersheds: hydroeconomic simulations of water sharing policies between upstream small private irrigators and downstream large public irrigation schemes in Burkina Faso

A spatial hydroeconomic model was developed to analyze the competition between small private (SPIS) and large public (LPIS) irrigation systems for water control in tropical watersheds and applied to several water allocation policies in Kou watershed in Burkina Faso. Capital (cash and motorpumps) is the main constraining factor for SPIS expansion, and capital inflow accelerates SPIS development and reduces water flows for downstream LPIS users. As SPIS is more cost-effective and less water thirsty, LPIS needs to shift to less water-demanding and high-value crops or adopt more water-saving practices. Otherwise, only a sharp rice yield increase in LPIS can justify a reserved water quota for downstream users.     

High-throughput analysis of thin-film stresses using arrays of micromachined cantilever beams

We report on a technique for making high-throughput residual stress measurements on thin films by means of micromachined cantilever beams and an array of parallel laser beams. In this technique, the film of interest is deposited onto a silicon substrate with micromachined cantilever beams. The residual stress in the film causes the beams to bend. The curvature of the beams, which is proportional to the residual stress in the film, is measured by scanning an array of parallel laser beams generated with a diffraction grating along the length of the beams. The reflections of the laser beams are captured using a digital camera. A heating stage enables measurement of the residual stress as a function of temperature. As the curvature of each beam is determined by the local stress in the film, the film stress can be mapped across the substrate. This feature makes the technique a useful tool for the combinatorial analysis of phase transformations in thin films, especially when combined with the use of films with lateral composition gradients. As an illustration, we apply the technique to evaluate the thermomechanical behavior of Fe-Pd binary alloys as a function of composition.