Function Of Load Factor Research Articles

Response of sandy soil to the volume losses at the tunnel face level

Recent research does not fully identify the causes of surface volume loss that occur at the tunnel level in sand, as related to the excavation of a pressurized-face tunnel boring machine (PTBM). This paper focuses on the face stability of PTBM tunneling, and the response of sandy soil to the inadequate face pressure is evaluated. Data presented are from tests of a model using reduced-scale PTBM tunneling operations in dry sand. Ground displacement and the evolution of ground stress were analyzed. The relationship between the load factor at the face and the volume loss at surface was examined. The effects of soil density and tunnel depth were considered. An empirical formulation was provided allowing determination of the expected volume loss as a function of load factor (LF), cover-to-diameter ratio (C/D) and soil density (Id). Thus providing a valuable basis for establishing relationship between volume loss associated with tunnel face advancement and face pressures in sandy soil. The results show that instability of the face is accompanied by the triggering of secondary deformation mechanisms at the surface. The volume loss at surface is complicated by the combined effects of soil arching and the dilative/contractive behavior of the soil. The variation of volume loss is sudden prior to face collapse, especially at dense sand, which is different from the progressive variation of volume loss in clays. The size of destressed zone ahead of cutter head is less dependent on C/D in loose soil than in dense soils.

Singularities Analysis of the Jacobian Matrix Modified in the Continuation Power Flow: Performance Evaluation

In the literature, a study to analyze stability and voltage instability is related to the P-V curve (power versus voltage magnitude) and the maximum loading point (MLP) (point on the curve that separates the stable operation of the unstable). The maximum loading point may be consequent to a saddle node bifurcation (SNB) related to transmission capacity limit in an electrical system where the Jacobian matrix is singular, or limit induced bifurcation (LIB), related the reactive power limit of the generator, where the matrix is not singular. In this sense, it is presented in this second part of the paper the trajectory of the values of the determinants of the modified Jacobian matrices (|Jm|) of these methods. A graphical analysis is also shown for a better understanding. The methods studied are: local parameterization, global parameterization (total real power losses (Pa), angular coefficient at the plane defined by sum of the magnitudes of nodal voltage (Vk) or angles (k)) as a function of loading factor and the quadratic equation in Pa plane in function of loading factor. The results are obtained for the IEEE test systems 14 and 300 buses. A study in the MLP is performed in order to verify that the point corresponds to a saddle node bifurcation (SNB) or a limit induced bifurcation (LIB).

Load-Aware Energy Efficiency Optimization in Dense Small Cell Networks

Energy efficiency (EE) has become a crucial metric in dense small cell networks (DSCNs) due to the tremendous escalation of energy consumption. Since small cell base stations (SBSs) are randomly deployed, loads of them are usually different. In this letter, we aim to maximize the load-aware weighted sum of EEs (LWSEEs) across all subchannels in DSCNs jointly considering SBSs’ loads and users’ signal processing power through power allocation. First, we design the EE weight as a function of load factor (LF). Then, the LWSEE optimization problem is formulated as a non-concave sum-of-ratios optimization and we present the optimal LWSEE algorithm to tackle the problem based on the concave-convex procedure method. Furthermore, a simplified LWSEE (LWSEE-simp) algorithm where SBSs form interference groups is developed to reduce the signaling overhead in DSCNs. Simulation results show that SBSs’ sum-EEs can be optimized according to their LFs and the optimal interference group size exists in the LWSEE-simp algorithm.

Passive load following method for PEFC system with reformer and its efficiency improvement evaluated by using the concept of exergy

The Metal-Hydride Intermediate-Buffer (MIB) method, which enables the load following operation of the PEFC system with reformer, has been proposed. Feasibility of this system has already been confirmed experimentally and the result shows that the metal hydride is not poisoned with impurities in reformed gas. It is expected that the MIB method improves the efficiency of PEFC systems especially in low load. Efficiency improvement in low load of the PEFC system for residential use is important because the average electric power consumption in general residences is about 10 to 20% of the peak power. In this paper, the PEFC system efficiency using the MIB method is evaluated by the concept of exergy. The exergy efficiency of this system has been calculated and compared with the conventional system as a function of load factor. The result shows that the efficiency of our system is higher especially at lower load factor, but slightly lower at the rated condition than that of the conventional system. The obtained relation between the load factor and the exergy efficiency has been adapted to load demand patterns for one year measured at a residence. The results show that maximum exergy efficiency of the system with the MIB method is 4.5% higher than that of the conventional system, and the system efficiency with the MIB method is higher than the conventional system above 900 W of rated power. The PEFC system for residential use is being investigated mainly for a 1-kW-class generator. It has been clarified that the PEFC system with the MIB method has an ability to improve the efficiency at 1 kW rated power and passive load following function that the conventional systems never have. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(4): 17–26, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20148

Passive Load Following Method for PEFC System with Reformer and its Efficiency Improvement Evaluated by Using the Concept of Exergy

The Metal Hydride Intermediate-Buffer (MIB) method, which enables the load following operation of the PEFC system with reformer, has been proposed. Feasibility of this system has been already confirmed by the experiment and the result shows that metal hydride is not poisoned with impurities in reformed gas. It is expected that the MIB method improves the efficiency of PEFC system especially in low load. Efficiency improvement in low load of the PEFC system for residential use is important because the average electric power consumption in general residences is about 10-20% of the peak power. In this paper the efficiency of PEFC system with MIB method is evaluated by using the concept of exergy. The exergy efficiency of this system has been calculated and compared with the conventional system as a function of load factor. The result shows that efficiency of our system is higher especially in lower load factor, but slightly lower at the rated condition than that of the conventional. The obtained relation between the load factor and the exergy efficiency has been adapted to load demand patterns for one year measured at a residence. The results show that maximum exergy efficiency of the system with the MIB method is 4.5% higher than that of the conventional system, and the system efficiency with the MIB method is higher than the conventional system above 900W of rated power. The PEFC system for residential use is being investigated mainly about 1kW class generator. It has been clarified that the PEFC system with the MIB method has an ability to improve the efficiency at 1kW rated power and the passive load following function that the conventional systems never have.

Turn Performance of Aircraft

The turn radius of an aircraft is calculated as a function of load factor, simplifying the problem of determining the airspeed and angle of bank for a minimum radius turn.