Interface of the transport systems research vehicle monochrome display system to the digital autonomous terminal access communication data bus

An upgrade of the transport systems research vehicle (TSRV) experimental flight system retained the original monochrome display system. The original host computer was replaced with a Norden 11/70, a new digital autonomous terminal access communication (DATAC) data bus was installed for data transfer between display system and host, while a new data interface method was required. The new display data interface uses four split phase bipolar (SPBP) serial busses. The DATAC bus uses a shared interface ram (SIR) for intermediate storage of its data transfer. A display interface unit (DIU) was designed and configured to read from and write to the SIR to properly convert the data from parallel to SPBP serial and vice versa. It is found that separation of data for use by each SPBP bus and synchronization of data tranfer throughout the entire experimental flight system are major problems which require solution in DIU design. The techniques used to accomplish these new data interface requirements are described

Intergranular stress distributions in polycrystalline aggregates of irradiated stainless steel

In order to predict InterGranular Stress Corrosion Cracking (IGSCC) of post-irradiated austenitic stainless steel in Light Water Reactor (LWR) environment, reliable predictions of intergranular stresses are required. Finite elements simulations have been performed on realistic polycrystalline aggregate with a recently proposed physically-based crystal plasticity constitutive equations validated for neutron-irradiated austenitic stainless steel. Intergranular normal stress probability density functions are found with respect to plastic strain and irradiation level, for uniaxial loading conditions. In addition, plastic slip activity jumps at grain boundaries are also presented. Intergranular normal stress distributions describe, from a statistical point of view, the potential increase of intergranular stress with respect to the macroscopic stress due to grain-grain interactions. The distributions are shown to be well described by a master curve once rescaled by the macroscopic stress, in the range of irradiation level and strain considered in this study. The upper tail of this master curve is shown to be insensitive to free surface effect, which is relevant for IGSC

Market games and successive oligopolies

This paper first introduces an approach relying on market games to examine how successive oligopolies do operate between downstream and upstream markets. This approach is then compared with the traditional analysis of oligopolistic interaction in successive markets. The market outcomes resulting from the two approaches are analysed under different technological regimes, decreasing vs constant returns.successive oligopolies, market games, entry, double marginalization

Market Games and Successive Oligopolies

This paper first introduces an approach relying on market games to examine how successive oligopolies do operate between downstream and upstream markets. This approach is then compared with the traditional analysis of oligopolistic interaction in successive markets. The market outcomes resulting from the two approaches are analysed under different technological regimes, decreasing vs constant returnsD43, L1, L13, L22

Cooperatives for staple crop marketing: Evidence from Ethiopia

Rural producer organizations, such as farmers' organizations or rural cooperatives, offer a means for smallholder farmers in developing countries to sell their crops commercially. They hold particular promise for Sub-Saharan Africa, where small-scale farming is the primary livelihood but commercialization of foodcrops is very limited. Using the experience of smallholders in Ethiopia as a case study, this research monograph identifies the benefits of rural producer organizations for small farmers, as well as the conditions under which such organizations most successfully promote smallholder commercialization. The evidence from Ethiopia indicates that they do increase farmers' profits from crop sales, but that the beneficiaries do not tend to be the poorest smallholders. Moreover, a rural producer organization's marketing effectiveness is precarious: it can easily diminish if the number or diversity of its members increases or if it provides more nonmarketing services. The authors conclude that these organizations have a role to play in the agricultural development of Sub-Saharan Africa, but that role should be complemented by other programs that directly target the poorest farmers. Further, the effectiveness of rural producer organizations should be preserved by allowing them to follow their own agendas rather than being encouraged to take on nonmarketing activities. The assessment of rural producer organizations presented in this monograph should be a valuable resource for policymakers and researchers concerned with economic development and poverty reduction in Sub-Saharan Africa.Agricultural development, economic growth, Food security Africa, Poverty reduction, Rural poverty, Rural producer organizations (RPOs), Smallholders,

Continuum limit of amorphous elastic bodies (III): Three dimensional systems

Extending recent numerical studies on two dimensional amorphous bodies, we characterize the approach of elastic continuum limit in three dimensional (weakly polydisperse) Lennard-Jones systems. While performing a systematic finite-size analysis (for two different quench protocols) we investigate the non-affine displacement field under external strain, the linear response to an external delta force and the low-frequency harmonic eigenmodes and their density distribution. Qualitatively similar behavior is found as in two dimensions. We demonstrate that the classical elasticity description breaks down below an intermediate length scale $\xi$, which in our system is approximately 23 molecular sizes. This length characterizes the correlations of the non-affine displacement field, the self-averaging of external noise with distance from the source and gives the lower wave length bound for the applicability of the classical eigenfrequency calculations. We trace back the "Boson-peak" of the density of eigenfrequencies (obtained from the velocity auto-correlation function) to the inhomogeneities on wave lengths smaller than $\xi$.Comment: 27 pages, 11 figures, submitted to Phys. Rev.

Particle displacements in the elastic deformation of amorphous materials: local fluctuations vs. non-affine field

We study the local disorder in the deformation of amorphous materials by decomposing the particle displacements into a continuous, inhomogeneous field and the corresponding fluctuations. We compare these fields to the commonly used non-affine displacements in an elastically deformed 2D Lennard-Jones glass. Unlike the non-affine field, the fluctuations are very localized, and exhibit a much smaller (and system size independent) correlation length, on the order of a particle diameter, supporting the applicability of the notion of local "defects" to such materials. We propose a scalar "noise" field to characterize the fluctuations, as an additional field for extended continuum models, e.g., to describe the localized irreversible events observed during plastic deformation.Comment: Minor corrections to match the published versio