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991.
R. Giovanelli 《Il Nuovo Cimento D》1987,9(11):1443-1460
Summary Using the Boris mover, or other standard methods, the error pile-up in the computation of the relativistic orbit of charged
particles in electric and magnetic fields becomes quickly excessive, if one wants to keep reasonably limited the number of
points employed to build the particle orbit. An analytical solution becomes, therefore, desirable and its construction is
the subject of the present work.
Riassunto Unsando il metodo di Boris, oppure altri metodi standard, l'accumulazione degli errori nella determinazione numerica delle orbite relativistiche di particelle cariche in campi elettrici e magnetici diventa intollerabile, se il numero dei punti impiegati per costruire le orbite stesse è mantenuto basso. Una soluzione analitica diviene quindi utile, e questa costituisce l'argomento del presente lavoro.
Резюме В рамках стндартных методов погрешность при вычислении релятивистской орбиты заряженных частиц в электронном и магнитном полях становится чрезмерно большой, если для построения орбиты часицы используется ограниченное число точек. В связи с этим конструируется аналитическое решение.相似文献
992.
993.
M. H. Saffouri 《Il Nuovo Cimento D》1986,7(2):175-194
Summary A treatment of transition radiation is presented. This is based on the fields produced by the polarization charges in the
radiation zone. These charges are extracted from the exact forms of the fields which were derived previously. A distinction
is found between the radiation in the forward and in the backward regions. This would call for experimental verification.
Comparison with other treatments shows similarity in the general features but important differences in the details.
Riassunto Si presenta una trattazione della radiazione transitoria. Essa è basata sui campi emessi nella regione asintotica dalle cariche di polarizzazione. Queste cariche sono estratte dalle forme esatte di campi che erano stati precedentemente derivati. Si verifica una distinzione chiara fra la radiazione nella direzione avanti e indietro. Questo neccesiterebbe una verifica sperimentale. Il confronto con altri trattamenti mostra una somiglianza nelle linee generali ma anche importanti differenze nei dettagli.相似文献
994.
Özgür Kabak Füsun Ülengin Emel Aktaş Şule Önsel Y. Ilker Topcu 《European Journal of Operational Research》2008
Efficient workforce scheduling has an important impact on store profit and customer service. Standard scheduling problems do not recognize the effect of staff availability on customer sales, however, even though the latter is an important factor in the retail sector. In this paper a two-stage model is proposed for this purpose. In the first stage a sales response model is used to specify hourly staff requirements. The output of the sales response model is then used as the input of a mixed integer optimization model, which finds an optimum assignment of the staff to daily shifts. Simulations are used to validate the sales response function, and to revise the model for more accurate results. In the simulations, customer arrivals and sales response error values are generated using appropriate distribution functions. As a case study the proposed model is applied to a Turkish retailer in the apparel sector. 相似文献
995.
We consider the kernel estimation of a multivariate regression function at a point. Theoretical choices of the bandwidth are possible for attaining minimum mean squared error or for local scaling, in the sense of asymptotic distribution. However, these choices are not available in practice. We follow the approach of Krieger and Pickands (Ann. Statist.9 (1981) 1066–1078) and Abramson (J. Multivariate Anal.12 (1982), 562–567) in constructing adaptive estimates after demonstrating the weak convergence of some error process. As consequences, efficient data-driven consistent estimation is feasible, and data-driven local scaling is also feasible. In the latter instance, nearest-neighbor-type estimates and variance-stabilizing estimates are obtained as special cases. 相似文献
996.
An analytical solution for the model of drug distribution and absorption in small intestine 总被引:2,自引:0,他引:2
Xu Mingyu 《Acta Mechanica Sinica》1990,6(4):316-323
According to the physiological and anatomical characteristics of small intestine, neglecting the effect of its motility on
the distribution and absorption of drug and nutrient, Y. Miyamoto et al.[1] proposed a model of two-dimensional laminar flow in a circular porous tube with permeable wall and calculated the concentration
profile of drug by numerical analysis. In this paper, we give a steady state analytical solution of the above model including
deactivation term. The obtained results are in agreement with the results of their numerical analysis. Moreover the analytical
solution presented in this paper reveals the relation among the physiological parameters of the model and describes the basic
absorption rule of drug and nutrient through the intestinal wall and hence provides a theoretical basis for determining the
permeability and reflection coefficient through in situ experiments.
The project supported by NSF of Shandong Province 相似文献
997.
R. Bracco E. Canessa M. R. Cimberle C. Ferdeghini M. Putti A. S. Siri 《Il Nuovo Cimento D》1987,9(3):289-300
Summary We have performed quantum Hall effect measurements on commercial low-mobilityn-channel MOSFETs. The channel resistancevs. electron concentration has the expected oscillating behaviour and gives the quantized values for the Hall resistance, at
least in the region of higher mobility. One class of the tested samples gave a surprising behaviour, both in QHE and in field
effect mobility measurements: this is thought to be due to uncontrolled differences in the diffusion zones at the interface
between the channel and the contacts. In particular, we attribute the deformation of the QHE curves to the onset of a thermoelectromotive
force which is present in the electron gas even if the sample is isothermal. A clear evidence for thermoelectric effects is
given by measurements made on a high-quality Hall geometry MOSFET.
Riassunto Abbiamo eseguito misure di effetto Hall quantistico su MOSFET commerciali di bassa mobilità a canalen. Le curve di resistenza di canale in funzione della tensione di gate presentano l'atteso andamento oscillante e danno i valori quantizzati, almeno nelle regioni di maggiore mobilità. Una categoria di campioni ha mostrato andamenti sorprendenti, sia in misure di QHE che in misure di mobilità per effetto di campo: riteniamo che ciò sia dovuto a differenze incontrollabili nelle regioni di diffusione alle interfacce tra i contatti e il canale. In particolare, attribuiamo la deformazione delle curve di QHE all'instaurarsi di forze termoelettromotrici, che sono presenti nel gas elettronico nonostante i campioni siano isotermi. Misure eseguite su un MOSFET a geometria Hall di alta qualità forniscono una chiara evidenza dell'esistenza di effetti termoelettrici.
Резюме Проводятся измерения квантового эффекта Холла на коммерческих MOSFET с малой подвижностью вn-канале. Зависмость сопротивления канала от концентрации электронов обнаруживает осцилляторное поведение и дает квантованные значения сопротивления Холла, по крайней мере, в области высокой подвижности. Один класс исследованных образцов обнаруживает удивительное поведение при измерении квантового эффекта Холла и при измерении зависимости подвижности от поля. Такое поведение, по-видимому, обусловлено неконтролируемыми различиями в зонах диффузии между каналом и контактами. В частности, мы приписываем деформацию кривых квантового эффекта Холла возникновению термоэлектродвижущей силы, которая присутствует в электронном газе, даже в изотермических образцах. Приводятся подтверждения для термоэлектрических эффектов, проводя измерения эффекта Холла в MOSFET с высокой подвижностью.相似文献
998.
999.
希尔伯特空间有限区域成像积分算子的谱 总被引:1,自引:0,他引:1
本文讨论了希尔伯特空间中有限区域成像积分算子的本征值和本征函数,研究了非对称核的情形,并用微扰和有限秩方法计算了衍射受限和离焦情况下的本征值和本征函数。 相似文献
1000.
R Srinivasan V Sankaranarayanan N P Raju S Natarajan U V Varadaraju G V Subba Rao 《Pramana》1987,29(2):L225-L230
The absolute thermopower of single phase YBa2Cu3O7 and Y0.8Er0.2Ba2Cu3O7 has been measured in the range 250 K to the superconducting transition temperature. It is found that these compounds show
a large enhancement of thermopower in the range 150 K down toT
c. This enhancement shows a steep exponential drop as the temperature increases from the transition temperature. The temperature
variation of the enhancement is too steep to be accounted for by electron-phonon or electron-local structural excitation mechanisms. 相似文献