Simple procedure for predicting long term average performance of nonconcentrating and of concentrating solar collectors

The Liu and Jordan method of calculating long term average energy collection of flat plate collectors is simplified (by about a factor of 4), improved, and generalized to all collectors, concentrating and nonconcentrating. The only meteorological input needed are the long term average daily total hemispherical isolation on a horizontal surface and, for thermal collectors the average ambient temperature. The collector is characterized by optical efficiency, heat loss (or U-value), heat extraction efficiency, concentration ratio and tracking mode. An average operating temperature is assumed. If the operating temperature is not known explicitly, the model will give adequate results when combined with the , f-chart of Klein and Beckman.A conversion factor is presented which multiplies the daily total horizontal insolation to yield the long term average useful energy delivered by the collector. This factor depends on a large number of variables such as collector temperature, optical efficiency, tracking mode, concentration, latitude, clearness index, diffuse insolation etc., but it can be broken up into several component factors each of which depends only on two or three variables and can be presented in convenient graphical on analytical form. In general, the seasonal variability of the weather will necessitate a separate calculation for each month of the year; however, one calculation for the central day of each month will be adequate. The method is simple enough for hand calculation.Formulas and examples are presented for five collector types: flat plate, compound parabolic concentrator, concentrator with east-west tracking axis, concentrator with polar tracking axis, and concentrator with 2-axis tracking. The examples show that even for relatively low temperature applications and cloudy climates (50°C in New York in February), concentrating collectors can outperform the flat plate.The method has been validated against hourly weather data (with measurements of hemispherical and beam insolation), and has been found to have an average accuracy better than 3 per cent for the long term average radiation available to solar collectors. For the heat delivery of thermal collectors the average error has been 5 per cent. The excellent suitability of this method for comparison studies is illustrated by comparing in a location independent manner the radiation availability for several collector types or operating conditions: 2-axis tracking versus one axis tracking; polar tracking axis versus east-west tracking axis; fixed versus tracking flat plate; effect of ground reflectance; and acceptance for diffuse radiation as function of concentration ratio.     

Brain-Derived Neurotrophic Factor (BDNF) Is Associated with Platelet Activity and Bleeding Tendency in Patients with Gaucher Disease

Bleeding tendency, a prominent feature of patients with Gaucher disease (GD), is associated with abnormal platelet function. Brain-derived neurotrophic factor (BDNF) is a protein with neuroprotective potential stored in alpha granules of circulating platelets. Here we studied BDNF levels in 50 patients with type I GD (GD1) and their correlation with platelet activity and bleeding tendency. Flow cytometry was used to test unstimulated and stimulated measurement of platelet surface-activated expression of αIIbβ3 integrin, P-selectin and lysosomal-associated membrane protein (LAMP3/CD63). Serum and plasma BDNF levels were quantified using ELISA. The bleeding history was recorded by a bleeding questionnaire. Serum BDNF levels were positively correlated with platelet count and moderately correlated with unstimulated and stimulated platelet P-selectin expression. Patients with more than one bleeding manifestation were shown to have lower serum BDNF levels, albeit similar platelet count. Plasma BDNF levels were significantly elevated in splenectomized patients and showed a moderate positive correlation with stimulated platelet CD63 expression. These observations demonstrate the first association between BDNF levels in the peripheral blood with platelet dysfunction and increased bleeding manifestation. The role of measuring serum BDNF for assessing platelet alpha degranulation defects and bleeding risk in patients with GD and the general population needs further study.     

Dynamic modelling of an industrial copper solvent extraction process

The dynamic behaviour of an industrial copper solvent extraction mixer–settler cascade is modelled to develop an advanced process control system. First, the process is introduced and the dynamical models are formulated. The testing environment is described and the successful results presented. Only industrially measured variables are required and plant-specific McCabe-Thiele diagrams are utilized to predict copper concentrations. The results with constant and adapted parameters are compared and the importance of parameter adaptation is discussed. Testing the simulator with adapted parameters over a period of 1 month of industrial operating data gave data that followed the real process measurements closely. In the future, the mechanistic models will be used for control system development and testing. The model can be used on all copper solvent extraction plants by modifying the flow configuration and adapting parameters.     

Fair and distributed peer-to-peer allocation of a common, refillable resource

We consider the general problem of distributed and fair peer-to-peer (P2P) allocation of a common, refillable resource. This problem recurs in a number of scenarios, for example grid computing, content distribution, Internet Service Provider service sharing, and distributed file storage over asymmetric channels. We present several distributed schemes for this allocation problem and show that these schemes guarantee two key properties: (i) asymptotic fairness, in that (even maliciously colluding) users are proportionally assigned resources corresponding to what they contribute; (ii) natural incentive to join and cooperate fairly in the system. We demonstrate the practicability of our approaches on a prototype P2P file storage system designed for typical residential Internet connections, in which download capacities often significantly exceed upload capacities. Our implementation shares file data when communications are idle using random linear codes so that, when needed, an end-user can download a file from several sources at a higher data rate than his home computer’s upload capacity. We present experimental results that support our analytical guarantees.     

Methods for modelling the ultimate strength of orthotropic plate with a central hole under uniaxial tension

The stress state in plates with circular holes made of orthotropic homogeneous material has no singularities and it can be exactly determined. The numerical stress distribution calculation by the finite element method will be compared with those obtained by the analytical equations developed by several authors. The goal of this work is to validate the finite element method, in conjunction with in-plane and out of plane failure criteria, in order to calculate not only the stress distribution for orthotropic plates with circular holes but also to determine their ultimate strength.The tool used has been a user subroutine (UMAT) specially developed for this work that implements the features of the commercial FE program (ABAQUS). The code performs an implicit analysis of the stress-state with progressive damage modelling.Finally, both of them, numerical and analytical method, will be checked with experimental tests by means of strain gauges.     

Organizational emergence in networked collaboration

Research on complex adaptive systems has generated several conceptual parables to explain systems with emergent behaviour. One prominent use for terms such as self‐organization, evolutionary trajectories, co‐evolution and punctuated equilibrium has been in understanding human organizations. In such systems, emergent behaviour is demonstrated in novel structures, processes and spin‐offs that cannot be explained just by studying single components of the organization and the intelligence embedded in them. Instead of solely exploiting the qualitative explanatory power of the evolutionary concepts, this paper focuses also on quantitative methods to track emergent behaviour in a globally distributed, constantly fluctuating and highly networked project organization. The underlying case is that of CERN (CERN, the European Laboratory for Particle Physics, has its headquarters in Geneva. At present, its Member States are Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, the Slovak Republic, Spain, Sweden, Switzerland and the United Kingdom. Israel, the Russian Federation, Turkey, Yugoslavia (status suspended after the UN embargo, June 1992), the European Commission and UNESCO have observer status.) and its decade long accelerator project, which strongly relies on electronic communication and networking to achieve its major objectives due to be accomplished by the year 2006. By using time series and self‐organizing maps to analyse the global interaction among project groups and individuals the paper provides new insight to the understanding of emergent behaviour in human organizations. The key result of the study concerns the rigid deep structure of each case organization that seems to remain intact for the duration of the whole project. Copyright © 2002 John Wiley & Sons, Ltd.     

Debris fragment characterization in oblique hypervelocity impacts

A case history in debris characterization is presented for oblique impacts of chunky tungsten projectiles against thin plates. The integrated approach of scaled experiments and hydrocode simulations led to a semi-analytic model of behind the plate debris fragment distributions. This debris distribution model agreed quite well with the experimental fragment distributions derived from witness plate measurements. The 1/4 scale test program included three projectile masses, two target geometries (single and dual plates), a velocity range of 4–7 km/s and a strike angle range of 15–55 degrees. Close correlation of measured and predicted fragment distributions encouraged the extension of the model to higher velocities not currently obtainable in the laboratory.

The paper also includes discussions of critical features of debris in oblique hypervelocity impact, the scalability of fragment data, and the utilization of the derived fragment models in semi-analytic damage assessment codes.     

A Gray Seal's (Halichoerus grypus) Responses to Experimenter-Given Pointing and Directional Cues.

A gray seal (Halichoerus grypus) was trained to touch a target on its left or right by responding to pointing signals. The authors then tested whether the seal would be able to generalize spontaneously to altered signals. It responded correctly to center pointing and head turning, center upper body turning, and off-center pointing but not to head turning and eye movements alone. The seal also responded correctly to brief ipsilateral and contralateral points from center and lateral positions. Pointing gestures did not cause the seal to select an object placed centrally behind it. Like many animals in similar studies, this gray seal probably did not understand the referential character of these gestures but rather used signal generalization and experience from initial operant conditioning to solve these tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implementing interactive applications in C++

This paper presents an object-oriented approach for the implementation of interactive systems. This approach applies the model-view-controller (MVC) paradigm, which is modified for the C++ environment. The modified paradigm is called MVC++. In this approach the design of interactive applications starts by constructing an object model that represents the key concepts of the problem domain. This object model does not contain any user interface elements. According to the MVC++ approach, the object model is called the model part of the application. Only after the model part has been created, is the user interface designed. A collection of user interface classes is called the view. The classes that connect the model and the view form the controller, which is designed to communicate with both the model and the view. The approach presented in this paper provides a number of benefits. Advantages of the original MVC approach are obtained in a standard C++ environment, the structure of applications becomes clear and stable, and reusability as well as readability of the classes increases. Reusability is achieved by employing a mechanism called ‘abstract partners’. The approach presented in this paper is being applied in the development of a large network management system with over one million lines of C++ code running in the XII environment.     

A ranked order filter implementation for parallel analog processing

Order statistic filtering, the generalization of which is ranked order filtering, is needed for many image-processing functions including median filtering and mathematical morphology. Combining order statistic functionality with the parallel operation and local connectivity of array processing approaches such as the cellular nonlinear network model, has the potential for very high performance in image processing. This paper examines the implementation of programmable ranked order extraction with a very compact hardware realization of an analog current-mode ranked order filter. The considerable savings in the required circuit area, compared to other circuits, make it possible to use the structure as a building block in a massively parallel signal processing array. The operation of the circuit is analyzed in detail with the help of simulations and measurement results obtained from a test chip manufactured in a 0.18-/spl mu/m standard digital CMOS technology are also presented. The simulations and measurement results verify the correct operation of the circuit and show that it is very suitable for inclusion in every cell of a large parallel processor array. This makes many grayscale processing functions available with truly parallel operation and therefore very high performance.