Effects Of System Characteristics Research Articles

Microbiological hydrogen (H2 ) thresholds in anaerobic continuous-flow systems: Effects of system characteristics.

Hydrogen (H2 ) concentrations that were associated with microbiological respiratory processes (RPs) such as sulfate reduction and methanogenesis were quantified in continuous-flow systems (CFSs) (e.g., bioreactors, sediments). Gibbs free energy yield (ΔǴ ~ 0) of the relevant RP has been proposed to control the observed H2 concentrations, but most of the reported values do not align with the proposed energetic trends. Alternatively, we postulate that system characteristics of each experimental design influence all system components including H2 concentrations. To analyze this proposal, a Monod-based mathematical model was developed and used to design a gas-liquid bioreactor for hydrogenotrophic methanogenesis with Methanobacterium bryantii M.o.H. Gas-to-liquid H2 mass transfer, microbiological H2 consumption, biomass growth, methane formation, and Gibbs free energy yields were evaluated systematically. Combining model predictions and experimental results revealed that an initially large biomass concentration created transients during which biomass consumed [H2 ]L rapidly to the thermodynamic H2 -threshold (≤1 nM) that triggerred the microorganisms to stop H2 oxidation. With no H2 oxidation, continuous gas-to-liquid H2 transfer increased [H2 ]L to a level that signaled the methanogens to resume H2 oxidation. Thus, an oscillatory H2 -concentration profile developed between the thermodynamic H2 -threshold (≤1 nM) and a low [H2 ]L (~10 nM) that relied on the rate of gas-to-liquid H2 -transfer. The transient [H2 ]L values were too low to support biomass synthesis that could balance biomass losses through endogenous oxidation and advection; thus, biomass declined continuously and disappeared. A stable [H2 ]L (1807 nM) emerged as a result of abiotic H2 -balance between gas-to-liquid H2 transfer and H2 removal via advection of liquid-phase.

PRIVATE DEVELOPERS’ PERCEIVED USEFULNESS OF THE PREFABRICATION TECHNOLOGY IN NIGERIA’S HOUSING DEVELOPMENT INDUSTRY

Private developers in Nigeria’s housing development industry still face challenges of increasing housing stock, with a current housing deficit of 20 million units. Prefabrication, a known, yet unpopular housing construction method, has witnessed low usage. The effect of system characteristics on user acceptance of prefabrication technology is examined through the Perceived Usefulness (PU), of prefabrication system amongst private developers in the Nigerian housing development. The paper draws on the technology acceptance model (TAM) as the basis for investigation. A quantitative research approach and convenient sampling technique to select 400 private developers- members of the Real Estate Developers Association of Nigeria (REDAN) in Lagos and Abuja. Data obtained were analyzed using descriptive analysis and Freidman’s ANOVA test. Findings showed that prefabrication amongst private developers in Nigeria is perceived as being highly useful for increasing housing stock. PU increases the degree of positivity toward usage, which subsequently triggers the intention to adopt.

Coupling transient behavior of primary frequency regulation of hydropower plant

This paper investigates the coupling transient behavior of primary frequency regulation of hydropower plant. Firstly, the model of hydropower plant with super long diversion tunnel under primary frequency regulation is established. Then, the stability is analyzed based on stable domain. The dynamic response is analyzed based on dynamic response process and indexes. The effects of system characteristics on stability and dynamic response are revealed. Finally, the coupling effect of head loss nonlinearity of super long diversion tunnel and water hammer elasticity of penstock on transient behavior is studied. The results indicate that the coupling effect of head loss nonlinearity of super long diversion tunnel and water hammer elasticity of penstock on transient behavior is influenced by sectional area of surge tank. With the decrease of sectional area of surge tank, the effect of water hammer elasticity of penstock is gradually weakened, while the effect of head loss nonlinearity of super long diversion tunnel is gradually strengthened. When the sectional area of surge tank is greater than critical stable value, the effect of water hammer elasticity of penstock plays a dominant role. The water hammer elasticity of penstock is unfavorable for the stability and dynamic response of primary frequency regulation.

Effects of high-altitude electromagnetic pulse on overhead pipeline

High-altitude electromagnetic pulse may cause damage to electronic equipments through coupling pipeline system. In order to study the effects of high-altitude electromagnetic pulse on overhead pipeline, the electromagnetic field-to-overhead pipeline coupling equations are derived from Maxwell’s equ ations. The coupling equations are solved in frequency domain by applying the Green’s functions, and the time-domain waveforms of induced currents and voltages are obtained by using inverse Fourier transform. The currents and voltages at both ends and in the middle of pipeline are calculated by MATLAB software. It is shown that the peak values of the currents along the pipeline don’t vary much. The voltages at the ends of the pipeline are larger and the voltage polarity at one end is opposite to another, while the voltages in the middle of the pipeline are smaller. The effects of system characteristics on induced voltages are presented, such as the length of the pipeline, the height of the pipeline, the radius of outer surface of the pipeline and the conductivity of the ground. The results of these studies are applicable to electromagnetic pulse protection.

The Effect of System Characteristics on Very-Short-Term Load Forecasting

The Effect of System Characteristics on Very-Short-Term Load Forecasting

Effects of System Characteristics on Geomagnetically Induced Currents

The geomagnetically induced currents (GICs) produced in power systems during magnetic storms are a function of the electric-field amplitude and direction, and the characteristics of the power system. This paper examines the influence of a number of power system characteristics, which include the resistances and structures of the conductors; the length of the transmission lines; the number, type, and resistances of transformers, the substation grounding resistances, and the topology of the network. It is shown that GIC grows with increasing line length but approaches an asymptotic constant value, and a more relevant parameter than the individual line length is the length of the entire system. This paper also derives the effective GIC for a conventional transformer and an autotransformer, and analyzes the behavior of GIC when the network topology changes illustrated with the GIC-Benchmark Model. The results of these studies provide a guide to estimating GIC impacts on a power network.

A Study on Effect of System Characteristics, Individual Characteristics, and Organization Characteristics on Information System for Public Administration

A Study on Effect of System Characteristics, Individual Characteristics, and Organization Characteristics on Information System for Public Administration

The Effect of System Characteristics, Stage of Adoption, and Experience on Institutional Explanations for ERP Systems Choice

SYNOPSIS: Existing studies have found a linkage between institutional factors and systems adoption, but the literature has overlooked an important question: When is the decision to implement a system influenced by institutional factors? In this paper, the author argues that decisions to adopt systems are not influenced equally by institutional factors, and examines how system characteristics moderate the effects of institutional factors on adoption decisions, specifically decisions to adopt enterprise resource planning (hereafter, ERP) systems. The results of the study reveal that institutional factors, such as mimicry of peers, compliance with industry norms, and coercion from powerful entities influence ERP adoption decisions. The results also show that the effects of institutional factors on adoption decisions are amplified when participants have not already adopted an ERP system, the benefits of the system are difficult to quantify, and the system enhances organizational interaction throughout the supply chain. Through this paper, the author contributes to the institutional theory literature by exploring conditions that enhance the salience of institutional factors and contributes to accounting information systems literature by investigating the boundaries of the influence of institutional factors on ERP adoption.

A New Approach for Power Flow Analysis of Balanced Radial Distribution Systems

Power flow analysis is perhaps the most useful technique in the design and operation of a power system. This paper reports on a new method of power flow analysis for solving balanced radial distribution systems. The proposed method models the radial distribution system as a series of interconnected ladder networks. Using Kirchoff's laws, a set of iterative power flow equations was developed to conduct the power flow studies. It is very efficient and has excellent convergence characteristics. The radial topology of distribution networks has been fully exploited such that a unique branch and node numbering scheme is utilized to achieve storage and computational economy. Due to the voltage dependency of loads in distribution systems, various static load models are incorporated in the power flow algorithm to obtain better and more accurate results. The computer software implemented in this power flow method was then developed using C++ and successfully applied to several practical radial distribution networks. The results were then validated with those obtained from using existing power flow analysis software. The performance of this method was found to be superior in terms of solution time and convergence characteristics to existing power flow methods. This paper also compares the power flow results of a distribution system for the different voltage-dependent load models. The convergence patterns of this power flow method for the various load models were also compared. In addition, the effects of system characteristics on the convergence of the method are highlighted.

The Effects of System Characteristics on Policy Implementation and Functioning of Care for the Elderly in France

In the early 1960s, old age in France was replaced by the notion of "troisième âge," a new definition stressing the possibility of pursuing social and leisure activities and greater independence. Old age itself was postponed to a later age, and acquired a purely negative image and one confused with that of incurable illness. As a result, a living-at-home policy was elaborated, and also a program of adapting institutions to the problems of those now defined as being in the "quatrième âge." This dual-faceted medicosocial policy was originally intended to be comprehensive and coordinated. Analysis of the structural characteristics of the care providers and of the agencies responsible for organization and financing of services shows fragmentation at the levels of service delivery and policy development. This prevents the coordination of service provision, gives rise to a mismatch between people and provision, and leads to a lack of coherent regulation and of adequate financing, in particular with regard to domiciliary care and social services. External factors, such as scarcity of funds related to the economic crisis, reinforce system dysfunctions.

Transient Diffusional Release from Waste Packages in a Repository in Basalt

AbstractAnalyses of diffusional release of several typical radionuclides in spent fuel from waste packages emplaced in a repository in basalt were conducted to assess the effects of system characteristics and boundary conditions on computed release rates. Radionuclide releases, including spatial and temporal variations that may be present, represent the source term for transport in the geohydrologic setting and are therefore critical to the assessment of repository acceptability.Two mathematical approaches were utilized to determine radionuclide release rate versus time characteristics; (1) an analytical solution for one-deimensional diffusion based upon a Dirichlet (constant-concentration) boundary at the waste form surface; and (2) a finite-element numerical solution based upon a Neumann (zero-flux boundary at the waste form surface. The latter method is suitable for radionuclides such as 129I, whose total inventory in spent fuel could be quickly depleted from the waste form and dissolved in the pore spaces of the packing material surrounding the waste form and which, therefore, cannot be adequately represented by a constant concentration at the waste form (i.e., container) surface.The analysis revealed several system characteristics that are not intuitively obvious. For example, strong sorption in the near-field host rock behaves like a strong mass sink and can yield calculated transient release rates exceeding allowable limits. Similarly, a short half-life effectively removes the radionuclide from the host rock, which induces a steep concentration gradient at the host rock/packing interface and thereby increases the diffusional release rate at that boundary.Typical results for 79Se and 129I are presented to illustrate these effects. The effects of perturbations to key assumptions are shown to indicate the importance of (1) formulating models that accurately represent the physical system and (2) interpreting analytical results carefully to ensure understanding of the capability of the system.