Conservative implicit schemes for the full potential equation applied to transonic flows

Implicit approximate factorization techniques (AF) were investigated for the solution of matrix equations resulting from finite difference approximations to the full potential equation in conservation form. For transonic flows, an artificial viscosity, required to maintain stability in supersonic regions, was introduced by an upwind bias of the density. Two implicit AF procedures are presented and their convergence performance is compared with that of the standard transonic solution procedure, successive line overrelaxation (SLOR). Subcritical and supercritical test cases are considered. The results indicate that the AF schemes are substantially faster than SLOR

Valuation of Safety-Branded and Traceable Free Range Chicken in Ha Noi: Results from a Field Experiment

The valuation of traceable or safety-branded food by consumers in developing countries affected by diseases such as avian influenza, or with food safety issues in general, is very difficult to identify. Products that have safety-branding are not common, and food is usually purchased by bargaining at informal markets. However, valuation of traceability has important implications for livestock disease policies as well as agricultural sector development. Through developing a short-term certified supply chain for free range chicken in Hanoi, we were able to conduct a combined field experiment and detailed household survey to measure the valuation of this type of poultry. We find that consumers in urban Hanoi on average have a welfare gain of about $1 per whole chicken purchase for safety-branding and traceability, which translates into a potential annual consumer welfare gain of$66 million for such characteristics.field experiments, avian influenza, Vietnam, food safety, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, C93, D12, Q13, Q18,

Credible Duck Food Safety Certification: Results of a Field Experiment

Food Security and Poverty,

A Bose-Einstein Approach to the Random Partitioning of an Integer

Consider N equally-spaced points on a circle of circumference N. Choose at random n points out of $N$ on this circle and append clockwise an arc of integral length k to each such point. The resulting random set is made of a random number of connected components. Questions such as the evaluation of the probability of random covering and parking configurations, number and length of the gaps are addressed. They are the discrete versions of similar problems raised in the continuum. For each value of k, asymptotic results are presented when n,N both go to infinity according to two different regimes. This model may equivalently be viewed as a random partitioning problem of N items into n recipients. A grand-canonical balls in boxes approach is also supplied, giving some insight into the multiplicities of the box filling amounts or spacings. The latter model is a k-nearest neighbor random graph with N vertices and kn edges. We shall also briefly consider the covering problem in the context of a random graph model with N vertices and n (out-degree 1) edges whose endpoints are no more bound to be neighbors

Predictions for the First Parker Solar Probe Encounter

We examine Alfv\'en Wave Solar atmosphere Model (AWSoM) predictions of the first Parker Solar Probe (PSP) encounter. We focus on the 12-day closest approach centered on the 1st perihelion. AWSoM (van der Holst et al., 2014) allows us to interpret the PSP data in the context of coronal heating via Alfv\'en wave turbulence. The coronal heating and acceleration is addressed via outward-propagating low-frequency Alfv\'en waves that are partially reflected by Alfv\'en speed gradients. The nonlinear interaction of these counter-propagating waves results in a turbulent energy cascade. To apportion the wave dissipation to the electron and anisotropic proton temperatures, we employ the results of the theories of linear wave damping and nonlinear stochastic heating as described by Chandran et al. (2011). We find that during the first encounter, PSP was in close proximity to the heliospheric current sheet (HCS) and in the slow wind. PSP crossed the HCS two times, namely at 2018/11/03 UT 01:02 and 2018/11/08 UT 19:09 with perihelion occuring on the south of side of the HCS. We predict the plasma state along the PSP trajectory, which shows a dominant proton parallel temperature causing the plasma to be firehose unstable.Comment: 16 pages, 5 figures; accepted for publication in the Astrophysical Journal Letter

Making Anti-de Sitter Black Holes

It is known from the work of Banados et al. that a space-time with event horizons (much like the Schwarzschild black hole) can be obtained from 2+1 dimensional anti-de Sitter space through a suitable identification of points. We point out that this can be done in 3+1 dimensions as well. In this way we obtain black holes with event horizons that are tori or Riemann surfaces of genus higher than one. They can have either one or two asymptotic regions. Locally, the space-time is isometric to anti-de Sitter space.Comment: LaTeX, 10 pages, 6 postscript figures, uses epsf.te

Innovative Design Concept for the New Bangkok International Airport, NBIA

Thermal and visual comfort for the occupants of a room are not defined by air temperature only, but also radiation with its three components solar radiation, daylight and heat radiation has to be taken into account (among other factors such as humidity, air speed and occupant activity and clothing levels). In hot climates the optimization of room comfort is a challenging task due to the high solar radiation over the whole year. In intelligent buildings new material developments are applied optimizing the building envelope in an integral building design process. New solutions for weather, noise and heat protection are developed, where building envelope and installed mechanical equipment work together creating optimal comfort at minimum energy consumption. This approach was used in the design of the New Bangkok International Airport, NBIA to develop an optimized building concept in a design team comprising the architects, structural and mechanical engineers, HVAC, acoustic and climate engineers