Low Memory Demands Research Articles

Scattering by cavity-backed antennas on a circular cylinder

Conformal arrays are popular antennas for aircraft, spacecraft, and land vehicle platforms due to their inherent low weight, drag, and observables. However, to date there has been a dearth of rigorous analytical or numerical solutions to aid the designer. In fact, it has been common practice to use limited measurements and planar approximations in designing such nonplanar antennas. We extend the finite element-boundary integral method to scattering by cavity-backed structures in an infinite, metallic cylinder. In particular, we discuss the formulation specifics, such as weight functions, dyadic Green's function, implementation details, and particular difficulties inherent to cylindrical structures. Special care is taken to ensure that the resulting computer program has low memory demand and minimal computational requirements. Scattering results are presented and validated as much as possible. >

The effects of competitive anxiety on memory span and rebound shooting tasks in basketball players

Two theoretical models were used to investigate aspects of basketball performance: Eysenck's (1979, 1984) compensatory arousal model and Humphreys and Revelle's (1984) twin resources model. Cognitive and somatic anxiety were manipulated using a 'time to event' paradigm. The aspects of performance were a short-term memory task (letter span) and a low memory demand, motoric-sustained information transfer task (rebound shooting). Hypotheses based on the different models were formulated and subsequently tested using analysis of variance and polynomial regression analysis. The results indicated significant (P < 0.01) linear relationships with negative slopes between cognitive anxiety and letter span, and between somatic anxiety and letter span; while significant (P < 0.01) linear relationships with positive slopes were recorded between cognitive anxiety and rebound shooting, and between somatic anxiety and rebound shooting. The analysis of variance results were in agreement with a positive effect (P < 0.05) for cognitive anxiety upon rebound shooting, and a negative effect which approached significance (P < 0.07) for somatic anxiety upon letter span. The results were interpreted as offering partial support for Eysenck's (1979) theoretical model, although further examination of multidimensional anxiety effects via the two models is warranted.

A discrete simulation model of electrocardiograms

A discrete simulation model reproducing electropotential changes within the heart and imitating the generation of the ECG signal has been developed using the SIMULA** language. Used for computational experiments, the current version is writ ten in FORTRAN IV because of lower memory demands and for installation on a desk-top computer. However, the FORTRAN version saves all important SIMULA methodology and enables different pathological situations of the cardiac conduction system to be modeled in a comparatively easy way. The present ver sion of the model is especially suited for projects studying car diac rhythm and its disorders. A large set of such experiments has been performed. This paper concisely describes the simulated system with special attention devoted to a description of the model principles and program results. Comparison is made be tween existing models of electrocardiogram generation, and some experimental results are shown. External validation of the model and advantages that have been obtained by transmitting the SIMULA model into FORTRAN are also discussed.