A simulation approach to the comparative analysis of various job scheduling methods

A simulation approach to the comparative analysis of different job scheduling methods with regard to CPU efficiency, the job throughput, and the job waiting time is presented. The job-processing simulation model is implemented in PL/1. In order to consider several possible dynamic situations for the job-scheduling methods, we simulated the job starting from its entry at the RJE (remote job entry) terminal until the job leaves the system, which includes an IBM 370/158 and AMDAHL 470 V/7. In particular, a Fourier series is used to predict the required CPU time for the job and to assign dynamically the internal priority for CPU scheduling. A detailed summary of conclusions that can be drawn from the simulation is given.     

Innovation in telecommunication and interfirm cooperative agreements

The purpose of this paper is to analyse the evolution towards the new paradigm of information and communication technology (ict) and its consequences in terms of strategies, in particular the development of cooperative agreements between telecommunication firms. To analyse the characteristics ofict paradigm we rely on some recent contributions in economics of technological change. We discuss in a second step the following proposition: an agreement is a flexible means to cope with increasing uncertainties and the durability of an agreement is conditioned by the search for a particular type of flexibility: dynamic and pro-active flexibility based on learning processes.     

A survey on industrial communication networks

Industrial communication networks differ from other types of networks because these applications are responsible for the control and monitoring of a physical process. In this paper, we will summarise the requirements that users specify for these networks, present the state of art on field buses, factory and cell communication networks and indicate current research directions.     

RCS reduction of a conducting cone-cylinder using an active method

This paper presents an active method for reducing the radar cross section (rcs) of a perfectly conducting cone-cylinder. The active elements are four microstrip patch antennas located symmetrically along the conecylinder axis. These elements radiate a field which permit the total scattered field in the direction of the receiver to be close to zero. In each time step, the hoarded system should determine some parameters of the incident wave: the incident direction, its frequency, amplitude, and phase. Then when antennas are fed with currents of suitable amplitude and phase, they radiate an electromagnetic field in the direction of the receiver that has the same amplitude but is opposite in phase compared to the scattered field, without feeding patches. Then the total field vanishes in the direction of the receiver.     

A Head Start for the 21st century.

Social and economic conditions since the creation of Head Start in 1965 have worsened. The stresses of economic restructuring in the US and the pervasiveness of violence have severely eroded the capacity of many families to provide safe and caring homes in strong communities. The necessary adaptation of Head Start to these new conditions involves the essential linkage of early childhood and family support approaches with community economic development. This strategy must include a reappraisal of mental health paradigms that will enable children, youth, and families to be healthy and productive members of their neighborhoods and country. Although public support for Head Start remains strong, considerable rethinking about a Head Start for the 21st century is now occurring; results will affect the quality of life for the entire society. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactions between components of the aggregation pheromone during chemotaxis by the bark beetleIps paraconfusus

The male-produced aggregation pheromone inIps paraconfusus is composed of three compounds. Female bark beetles were exposed to combinations of these compounds, presented as point sources in an enclosed, circular arena. By itself,cis-verbenol (cV) had no effect on the number of beetles that reached the source. Either ipsenol (Ip) alone or ipsdienol (Id) alone strongly increased the number that reached the source, with Id producing a dose-response curve with a much steeper slope. cV moved the onset of the response to Id to higher doses of Id, but the response rose more rapidly after onset than when cV was absent. Overall, cV inhibited the effect of Id except at the highest dose. cV affected the onset of the response to Ip little or none, but strongly increased the slope of the response, synergizing the effect of Ip. The responses to combinations of Id and Ip were related to the log of a linear combination of their doses. The results are consistent with a model where Id and Ip act at a single site of action, but with different potencies, while cV appears to modify the effects of Id and Ip, rather than affecting the site of action directly.     

A new instrument to assess the long-term quality of life effects from migraine: development and psychometric testing of the MSQOL

Quality of life is important to persons experiencing migraine. This study discusses the development of a migraine-specific quality-of-life measure (MSQOL). Participants, who included migraineurs from both tertiary care centers and the community, were screened using the International Headache Society migraine criteria prior to enrollment. Internal consistency of the MSQOL was high (alpha 0.92). Reproducibility over an average of 24 days was high (intraclass correlation 0.90). Construct validity was determined by convergent validity and known groups validity. The MSQOL was compared to two other frequently used health status questionnaires; results indicate that the MSQOL more closely resembles well-being than functional status. Results also indicate that migraineurs with more symptoms, medical appointments per year to treat migraines, and migraine episodes per year have a significantly worse quality of life. The MSQOL proved valid and reliable as a self-administered measure and will be a useful tool in clinical migraine research. The information gained from its use in the clinical environment should provide important additional information about the impact of migraine on quality of life and the potential benefits of therapeutic interventions.     

Age hardening and the potential for superplasticity in a fine-grained Al-Mg-Li-Zr alloy

Experiments were conducted to determine the age-hardening characteristics and the mechanical properties of an Al-5.5 pct Mg-2.2 pct Li-0.12 pct Zr alloy processed by equal-channel angular (ECA) pressing to give a very fine grain size of ∼1.2 μm. The results show that peak aging occurs more rapidly when the grain size is very fine, and this effect is interpreted in terms of the higher volume of precipitate-free zones in the fine-grained material. Mechanical testing demonstrates that the ECA-pressed material exhibits high strength and good ductility at room temperature compared to conventional Al alloys containing Li. Elongations of up to ∼550 pct may be achieved at an elevated temperature of 603 K in the ECA-pressed condition, thereby confirming that, in this condition, the alloy may be a suitable candidate material for use in superplastic forming operations.     

5.2-GHz bandwidth monolithic GaAs optoelectronic receiver

A high-speed monolithic optoelectronic receiver consisting of a photodetector, a transimpedance amplifier and a 50-Ω output buffer stage has been fabricated using an enhancement/depletion 0.35-μm recessed-gate GaAs MESFET process. The interdigitated metal-semiconductor-metal photodetector has a dark current of 0.8 nA, a responsivity of 0.2 A/W, and a capacitance of 12 fF. The bandwidth of the receiver is 5.2 GHz with an effective transimpedance of 300 Ω into a 50-Ω load, which corresponds to a transimpedance bandwidth product of 1.5 THz-Ω     

An EBIC equation for solar cells

When an electron beam of a scanning electron microscope (SEM) impinges on an N-P junction, the generation of electron-hole pairs by impact ionization causes a characteristic short circuit current I_SC to flow. The I_SC, i.e. EBIC (electron beam induced current) depends strongly on the configuration used to investigate the cell's response. In this paper we consider the case where the plane of the junction is perpendicular to the surface. An EBIC equation amenable to numerical computations is derived as a function of cell thickness, source depth, surface recombination velocity, diffusion length, and distance of the junction to the beam-cell interaction point for a cell with an ohmic contact at its back surface. It is shown that the EBIC equation presented here is more general and easier to use than those previously reported. The effects of source depth, ohmic contact, and diffusion length on the normalized EBIC characteristic are discussed.