A behavior model for blood donors and marketing strategies to retain and attract them

Objective: analyze and propose a theoretical model that describes blood donor decisions to help staff working in blood banks (nurses and others) in their efforts to capture and retain donors. Methods: analysis of several studies on the motivations to give blood in Spain over the last six years, as well as past literature on the topic, the authors' experiences in the last 25 years in over 15 Non Governmental Organizations with different levels of responsibilities, their experiences as blood donors and the informal interviews developed during those 25 years. Results: a model is proposed with different internal and external factors that influence blood donation, as well as the different stages of the decision-making process. Conclusion: the knowledge of the donation process permits the development of marketing strategies that help to increase donors and donations.

THEORETICAL ROAD DAMAGE DUE TO DYNAMIC TYRE FORCES OF HEAVY VEHICLES. PART 2: SIMULATED DAMAGE CAUSED BY A TANDEM-AXLE VEHICLE.

The literature relating to road surface failure and design is briefly reviewed and the conventional methods for assessing the road damaging effects of dynamic tire forces are examined. A new time domain technique for analyzing dynamic tire forces and four associated road damage criteria are presented. The force criteria are used to examine the road damaging characteristics of a simple tandem-axle vehicle model for a range of speed and road roughness conditions. It is concluded that for the proposed criteria, the theoretical service life of road surfaces that are prone to fatigue failure may be reduced significantly by the dynamic component of wheel forces. The damage done to approximately five per cent of the road surface area during the passage of a theoretical model vehicle at typical highway speeds may be increased by as much as four times.

What kind of friction model is needed to predict brake squeal?

Predictive models of friction-induced vibration have proved elusive despite decades of research. There are many mechanisms that can cause brake squeal; friction coupled systems can be highly sensitive to small perturbations; and the dynamic properties of friction at the contact zone seem to be poorly understood. This paper describes experimental and theoretical work aimed at identifying the key ingredients of a predictive model. A large-scale experiment was carried out to identify squeal initiations using a pin-on-disc test rig: approximately 30,000 squeal initiations were recorded, covering a very wide range of frequencies. The theoretical model allows for completely general linear systems coupled at a single sliding point by friction: squeal is predicted using a linearised stability analysis. Results will be presented that show that almost all observed squeal events can be predicted within this model framework, but that some subsets require innovative friction modelling: predictions are highly dependent on the particular choice of friction model and its associated parameters. Copyright © 2012 by ASME.

What kind of friction model is needed to predict brake squeal?

Predictive models of friction-induced vibration have proved elusive despite decades of research. There are many mechanisms that can cause brake squeal; friction coupled systems can be highly sensitive to small perturbations; and the dynamic properties of friction at the contact zone seem to be poorly understood. This paper describes experimental and theoretical work aimed at identifying the key ingredients of a predictive model. A large-scale experiment was carried out to identify squeal initiations using a pin-on-disc test rig: approximately 30,000 squeal initiations were recorded, covering a very wide range of frequencies. The theoretical model allows for completely general linear systems coupled at a single sliding point by friction: squeal is predicted using a linearised stability analysis. Results will be presented that show that almost all observed squeal events can be predicted within this model framework, but that some subsets require innovative friction modelling: predictions are highly dependent on the particular choice of friction model and its associated parameters. Copyright © 2012 by ASME.

Model for quantum efficiency of guided mode plasmonic enhanced silicon Schottky detectors

Plasmonic enhanced Schottky detectors operating on the basis of the internal photoemission process are becoming an attractive choice for detecting photons with sub bandgap energy. Yet, the quantum efficiency of these detectors appears to be low compare to the more conventional detectors which are based on interband transitions in a semiconductor. Hereby we provide a theoretical model to predict the quantum efficiency of guided mode internal photoemission photodetector with focus on the platform of silicon plasmonics. The model is supported by numerical simulations and comparison to experimental results. Finally, we discuss approaches for further enhancement of the quantum efficiency.

Theoretical gain of strained GeSn0.02/Ge1-x-y ' SixSny ' quantum well laser

Using effective-mass Hamiltonian model of semiconductors quantum well structures, we investigate the electronic structures of the Gamma-conduction and L-conduction subbands of GeSn/GeSiSn strained quantum well structure with an arbitrary composition. Our theoretical model suggests that the band structure could be widely modified to be type I, negative-gap or indirect-gap type II quantum well by changing the mole fraction of alpha-Sn and Si in the well and barrier layers, respectively. The optical gain spectrum in the type I quantum well system is calculated, taking into account the electrons leakage from the Gamma-valley to L-valley of the conduction band. We found that by increasing the mole fraction of alpha-Sn in the barrier layer and not in the well layer, an increase in the tensile strain effect can significantly enhance the transition probability, and a decrease in Si composition in the barrier layer, which lowers the band edge of Gamma-conduction subbands, also comes to a larger optical gain.

Kinetic Model Study on Enzymatic Hydrolysis of Cellulose Using Artificial Neural Networks

Enzymatic hydrolysis of cellulose was highly complex because of the unclear enzymatic mechanism and many factors that affect the heterogeneous system. Therefore, it is difficult to build a theoretical model to study cellulose hydrolysis by cellulase. Artificial neural network (ANN) was used to simulate and predict this enzymatic reaction and compared with the response surface model (RSM). The independent variables were cellulase amount X-1, substrate concentration X-2, and reaction time X-3, and the response variables were reducing sugar concentration Y-1 and transformation rate of the raw material Y-2. The experimental results showed that ANN was much more suitable for studying the kinetics of the enzymatic hydrolysis than RSM. During the simulation process, relative errors produced by the ANN model were apparently smaller than that by RSM except one and the central experimental points. During the prediction process, values produced by the ANN model were much closer to the experimental values than that produced by RSM. These showed that ANN is a persuasive tool that can be used for studying the kinetics of cellulose hydrolysis catalyzed by cellulase.

Biomimetic (topological) pattern recognition - A new model of pattern recognition theory and its application

A new theoretical model of Pattern Recognition principles was proposed, which is based on "matter cognition" instead of "matter classification" in traditional statistical Pattern Recognition. This new model is closer to the function of human being, rather than traditional statistical Pattern Recognition using "optimal separating" as its main principle. So the new model of Pattern Recognition is called the Biomimetic Pattern Recognition (BPR)(1). Its mathematical basis is placed on topological analysis of the sample set in the high dimensional feature space. Therefore, it is also called the Topological Pattern Recognition (TPR). The fundamental idea of this model is based on the fact of the continuity in the feature space of any one of the certain kinds of samples. We experimented with the Biomimetic Pattern Recognition (BPR) by using artificial neural networks, which act through covering the high dimensional geometrical distribution of the sample set in the feature space. Onmidirectionally cognitive tests were done on various kinds of animal and vehicle models of rather similar shapes. For the total 8800 tests, the correct recognition rate is 99.87%. The rejection rate is 0.13% and on the condition of zero error rates, the correct rate of BPR was much better than that of RBF-SVM.

Strain gradient theory based on a new framework of non-local model

A new framework of non-local model for the strain energy density is proposed in this paper. The global strain energy density of the representative volume element is treated as a non-local variable and can be obtained through a special integral of the local strain energy density. The local strain energy density is assumed to be dependent on both the strain and the rotation-gradient. As a result of the non-local model, a new strain gradient theory is derived directly, in which the first and second strain gradients, as well as the triadic and tetradic stress, are introduced in the context of work conjugate. For power law hardening materials, size effects in thin metallic wire torsion and ultra-thin cantilever beam bend are investigated. It is found that the result predicted by the theoretical model is well consistent with the experimental data for the thin wire torsion. On the other hand, the calculation result for the micro-cantilever beam bend clearly shows the size effect.

Multipolar model for collisional quantum interference on rotational energy transfer

A theoretical model of collisional quantum interference (CQI) is developed in a diatom-diatom system based on the first-order Born approximation of time-dependent perturbation theory and the multipolar interaction potential. The transition cross section is obtained. The relations between the differential and integral interference angles are discussed. The key factors on the determination of the differential and integral interference angles are obtained. The changing tendency of the interference angles with the experimental temperatures is obtained.

Process control in agile supply chain network.

The work comprises a new theoretical development applied to aid decision making in an increasingly important commercial sector. Agile supply, where small volumes of high margin, short life cycle innovative products are offered, is increasingly carried out through a complex global supply chain network. We outline an equilibrium solution in such a supply chain network, which works through limited cooperation and coordination along edges (links) in the network. The links constitute the stochastic modelling entities rather than the nodes of the network. We utilise newly developed phase plane analysis to identify, model and predict characteristic behaviour in supply chain networks. The phase plane charts profile the flow of inventory and identify out of control conditions. They maintain quality within the network, as well as intelligently track the way the network evolves in conditions of changing variability. The methodology is essentially distribution free, relying as it does on the study of forecasting errors, and can be used to examine contractual details as well as strategic and game theoretical concepts between decision-making components (agents) of a network. We illustrate with typical data drawn from supply chain agile fashion products.

A simple game-theoretic analysis of peering and transit contracting among Internet service providers

The paper presents a simple game-theoretic model of two Internet service providers (ISPs), drawn from a larger set consisting of Tiers-1 and -2 ISPs, who choose between peering and transit agreements. The study focuses on the costs of interconnection taking into account traffic imbalances. The analysis suggests that if the traffic flows and the costs of interconnection are fairly shared, the provider's peer, otherwise they choose transit. Moreover, the joint profits are maximized under the transit arrangement. Published by Elsevier Ltd.

Predictions of large events on a spring-block model

We study the predictability of a theoretical model for earthquakes, using a pattern recognition algorithm similar to the CN and M8 algorithms known in seismology. The model, which is a stochastic spring-block model with both global correlation and local interaction, becomes more predictable as the strength of the global correlation or the local interaction is increased.

A fluorescence model of the C3 radical in comets

Theoretical resonance fluorescence calculations are presented of the triatomic C3 radical and are compared with observations of the C3 emission in comets Hale-Bopp and de Vico. A theoretical model of the C3 vibration-rotational structure in the A1Piu - X1Sigmag + electronic system is introduced. The model takes into account the detailed structure of the bending mode nu2 which is responsible for the emission of the 4050 Å group. A total of 1959 levels are considered, with 515 levels in the ground state. The main effort is to model high-resolution spectra of the 4050 Å emission in comets C/1995 O1 Hale-Bopp and 122P/1995 S1 de Vico. The agreement between observed and theoretical spectra is good for a value of the dipole moment derivative of dmu/dr ~ 2.5 Debye Å-1. The modeled C3 emission exhibits a pronounced Swings effect. Based on observations made with William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, and on observations made at the McDonald Observatory, which is operated by the University of Texas at Austin, USA.

Hydraulics of stepped chutes: experimental-numerical-theoretical study

O estudo de escoamentos turbulentos em descarregadores em degraus tem sido um desafio para os investigadores. A macro-rugosidade do leito, a ondulação da superfície livre, a intermitência da localização da secção inicial de entrada de ar e o escoamento bi-fásico a jusante da secção inicial de entrada de ar fazem com que a caracterização do escoamento deslizante sobre turbilhões em descarregadores em degraus não seja simples. Actualmente, é possível combinar técnicas de medição fiáveis com simulações numéricas e análise teórica. Nesta dissertação, o estudo experimental baseia-se em resultados experimentais obtidos em duas instalações experimentais: a instalação A, do Laboratório Nacional de Engenharia Civil (LNEC), dotada de um descarregador em degraus com declive de 1V:0.75H e a instalação B, do Instituto Superior Técnico (IST), dotada de um descarregador em degraus com declive de 1V:2H. Uma sonda de ar, um tubo de Pitot modificado e vários hidrómetros permitiram o estudo do escoamento deslizante sobre turbilhões mono- e bifásico ao longo do descarregador em degraus da instalação A. Na bacia de dissipação de energia, a observação visual do escoamento foi auxiliada pelas leituras efectuadas em tomadas de pressão localizadas na soleira da bacia e pelas leituras da altura do escoamento efectuadas em réguas graduadas localizadas nas paredes da bacia. Na instalação B foram utilizados um tubo de Pitot e vários hidrómetros para estudar a região não arejada do escoamento deslizante sobre turbilhões no descarregador em degraus. O estudo numérico é baseado em simulações numéricas da região não arejada do escoamento deslizante sobre turbilhões sobre descarregadores em degraus com o código comercial de CFD FLOW-3D® de modo a reproduzir as condições ensaiadas experimentalmente. As simulações beneficiaram da técnica de blocos múltiplos (multi-block) num sistema de coordenadas cartesianas, da determinação da superfície livre pelo método TruVOF e da utilização de dois modelos de turbulência: os modelos k- e RNG k-. Por último, o estudo teórico consistiu em desenvolver um modelo simplificado 1D para determinar as características hidráulicas principais do trecho não arejado do escoamento deslizante sobre turbilhões em descarregadores em degraus. O modelo foi desenvolvido a partir das equações de Navier-Stokes, conjuntamente com resultados experimentais e numéricos. Os resultados apresentados nesta dissertação contribuem para o conhecimento do escoamento deslizante sobre turbilhões em descarregadores em degraus, nomeadamente na região não arejada, na secção inicial de entrada de ar e na região arejada. A hidráulica dos dissipadores de energia a jusante de descarregadores em degraus, em particular das bacias tipo III do USBR, é também objecto de estudo. Em relação à região não arejada do escoamento em descarregadores com declive acentuado, e com base em resultados experimentais e numéricos, são propostas expressões para estimar o desenvolvimento da altura equivalente de água, da espessura da camada limite, da concentração média de ar, do coeficiente de energia cinética, da dissipação de energia, do factor de resistência e do coeficiente n da fórmula de Manning. São ainda propostas expressões adimensionais para a energia cinética turbulenta e sua dissipação. Para declives moderados, são propostas expressões para estimar o desenvolvimento da altura equivalente de água, do coeficiente de energia cinética e da energia específica residual. São ainda apresentados valores do expoente 1/N da expressão adimensional da distribuição de velocidades, quer para descarregadores com declive acentuado quer com declive moderado. Em conformidade com outros estudos centrados em escoamentos de parede e com derivações teóricas, para a região não arejada do escoamento em descarregadores em degraus de acentuado declive, observa-se que o factor de resistência depende da macro-rugosidade criada pelos degraus e da geometria da secção transversal e que o coeficiente n da fórmula de Manning aumenta com a rugosidade. A descrição estatística da turbulência do escoamento é igualmente explorada, contribuindo para o conhecimento da estrutura do escoamento. Observou-se que para números de Reynolds rugoso não superiores a 6.8x104 a energia cinética turbulência e a sua dissipação cumprem leis de semelhança. Estas expressões adimensionais estão de acordo com os resultados obtidos por outros autores para escoamentos completamente desenvolvidos em canais abertos e no escoamento em rios com leito de gravilha. Em acréscimo, a taxa de dissipação de energia, quer para descarregadores de declive acentuado quer de moderado declive, é baixa. Por último, observa-se que os valores da média temporal da concentração de ar entre 0 e 1 medidos na região não arejada do escoamento dizem respeito não só ao ar capturado entre ondas de água, na zona de ondulação da superfície livre, mas também ao ar emulsionado no escoamento, i.e., sob a forma de bolhas de ar, quando perto da secção média inicial de entrada de ar, devido à diferença entre localizações instantânea e média temporal. Foram revistas metodologias e fórmulas para estimar a localização da secção inicial de entrada de ar e apresentadas expressões para estimar a concentração média de ar e a altura equivalente de água nessa secção. Relativamente à região de escoamento arejado em descarregadores em degraus com declive acentuado, os resultados experimentais apresentados nesta dissertação permitiram estimar a influência da definição da superfície livre nos parâmetros hidráulicos da região do escoamento arejado e estimar a máxima elevação do escoamento nesta região do escoamento. Com base nos resultados experimentais obtidos na bacia de dissipação de energia do tipo III do USBR localizada a jusante do descarregador em degraus da instalação A, observou-se que os perfis da altura piezométrica e da altura do escoamento tendem a seguir o perfil recomendado pelo USBR para bacias tipo III. A excepção ocorre à entrada da bacia, onde as alturas piezométricas apresentadas nesta dissertação excedem largamente as apresentadas pelo USBR. É ainda observado que, tal como entre as bacias tipo I e tipo III do USBR, o ressalto hidráulico estabiliza muito mais rapidamente numa bacia tipo III a jusante de um descarregador em degraus do que uma bacia tipo I a jusante do mesmo descarregador em degraus. Finalmente, observa-se que os blocos de amortecimento a colocar no descarregador não têm influência visível nos resultados da altura piezométrica nem da altura do escoamento ao longo da bacia. Relativamente às simulações numéricas do escoamento não arejado, a proximidade entre resultados experimentais e numéricos permite validar o modelo teórico e a integração numérica usados no FLOW-3D®. As simulações desenvolvidas também mostraram que o modelo de turbulência k- permite representar as características do escoamento não arejado em descarregadores em degraus, uma vez que não foram observadas diferenças significativas entre as simulações com este modelo e com o modelo RNG k-. Finalmente, observou-se que o modelo de entrada de ar usado no FLOW-3D® é válido para estimar a localização da secção inicial de entrada de ar. Por último, a proximidade entre os resultados obtidos da aplicação do modelo teórico desenvolvido no âmbito desta dissertação e os resultados experimentais indica que as hipóteses e simplificações consideradas no desenvolvimento do modelo são adequadas.