Papers by Keyword: Load

Abstract: This paper presents performance-based study of the Nigerian Transmission Grid (NTG), having about 27 power stations, 50 transmission (330/132kV) stations and 150 bulk load centers (132/33kV). Power stations and transmission grid are designed to operate at a level close to installed capacities, to achieve high efficiency. However, due to some technical limitations and maintenance factors, not all the elements may be available at all operating times. Therefore, the available generations may not equal the installed capacity; also, the load demand (consumed) on the grid may not equal the installed transmission capacities. This study evaluates the capacity of the transmission grid considering the installed and available generation capacity and three components of transmission load: actual load demand (LD), transmission wheeling capacity (TWC) and transmission load capacity (TLC). Obtained system data were used to create virtual simulator for the transmission grid, using Power System Analysis software (NEPLAN), which uses Newton Raphson Algorithm. The results established that the power generation on the grid must be maintained at the level of installed capacity to deliver the TWC and TLC load component to mitigate the practice of rotational power transmission and distributions currently being adopted in electricity transmission and distribution in Nigeria. It was established that the transmission capacity of the current transmission network is capable of accommodating and delivering power more than the current installed generation capacity. It is recommended that efforts be geared towards improving the generation capability of the grid for efficient power transmission and distribution. Keywords: grid capacity, transmission grid, load, system collapse, voltage stability

Abstract: High quality and behavior of steel is playing an essential role in metal and manufacturing industries. Hardox steel has exceptional properties includes high wear resistant and hardness. The wear behavior of hardox 400 steel was evaluated through pin on disc tribometer using different input constraints such as load, sliding velocity and disc speed. The wear worn surface was investigated through atomic force microscopy. The wear rate of the hardox steel was calculated with different load conditions. The wear factors and wear rate were optimized by taguchi method. Variance analysis was provided the contribution of each factor on mass loss.

Abstract: A metal extrusion was process that extrusion puncture perforate surface of material to throw and flow across outlet of die. This operation was a complex process in extrusion while penetration occurred at same time. This process can be seen in many production operations, like in forming of making portion of metal strip, and forming of extruded portion in a complex fineblanking with extrusion operation. Also exhibit the operation properties and give the method of numerical solution. So increasing load to 610KN with increased friction factor to 0.7 and increased with increasing the reduction ratio and stroke of operation. For the results and mesh distortion, with allocations of strains may be predicted. Analyzing results was submitted of metal extruded may be classified into two zones for the different lineaments deformation. moreover, energy in the zones of deformation may be classified into two parts for their different lineaments of internal zone and contact zone with the die . Fracture location has been found from simulations. Keyword Load, Extrusion, upper bound, numerical solution

Abstract: As a result of the research, the deformation properties of aluminosilicate adhesives modified with nitrate salts and intended for gluing wooden products and structures made of pine, beech and oak wood at different stages of their hardening were determined. Considering that pine is the most common wood in the manufacture of products and structures, then in order to reduce the numerical values of the elastic modulus in glued materials, it is advisable to add ammonium, lithium and sodium nitrates in an amount of 0.5%, potassium nitrate in an amount of 1% into the composition of an aluminosilicate adhesive. which will ensure the approximation of the elastic modulus values to the values of the unmodified aluminosilicate adhesive and will significantly affect the water resistance of the glue joint and the depth of penetration of the adhesive into the wood structure. For gluing beech wood products to reduce the elasticity modulus, it is advisable to introduce 0.5% ammonium and potassium nitrates and 1% lithium and sodium nitrates, which will reduce the numerical values of the elastic modulus in glued materials by 1.18 and 1.53 times compared with the values of the elastic modulus of the unmodified aluminosilicate adhesive. For gluing oak wood products to reduce the elasticity modulus, it is advisable to introduce 0.5% potassium nitrate and 1.5% sodium nitrate, which will reduce the numerical values of the elastic modulus in glued materials by 1.4 and 2.83 times compared to the values modulus of elasticity of unmodified aluminosilicate adhesive.

Abstract: In the article, the results of experimental researches of elements of structural steel reinforced slabs are presented. And the particularities of the work of structural designs under load are identified.

Abstract: The results of experimental and theoretical studies of the process of destruction of concrete by the methods of fracture mechanics are considered. Results of studies of long-term strength, durability and deformability of concrete subjected to a preliminary short-term temperature action up to 300° C and 400° C under load and without load are presented. It is shown that after short-term heating up to 300о С the long-term strength of concrete decreases insignificantly. It is established that heating up to 400° C can be considered the boundary of the structural integrity of concrete. The conditions for using the results of these studies in determining the values of a function that characterizes the change in the long-term strength of a material in the mechanics of heterogeneous structures are formulated. The function of the material destruction measure is introduced to describe the nature of the structural changes in the material at a given constant continuous load, and its change for different levels of a continuous load is considered.

Abstract: The nonlinear second-order differential eigenvalue problem describing eigenvibrations of a bar with elastically attached load is investigated. This problem has an increasing sequence of positive simple eigenvalues with limit point at infinity. The sequence of eigenvalues corresponds to a system of normalized eigenfunctions. The initial nonlinear eigenvalue problem is approximated by the quadrature finite element method on a uniform grid. The existence and accuracy of approximate solutions are studied. Investigations of the present paper can be generalized for the cases of more complicated and important problems on eigenvibrations of beams, plates and shells with elastically attached loads.

Abstract: In this work, vertically aligned titania nanotube arrays (TNTs) were fabricated on Ti surface in fluoride-containing electrolytes by anodization. TNTs were treated by hydrothermal treatment in the saturated solution of [Cu(NH₃)₄ (H₂O)₂]²⁺. Different hydrothermal treatment conditions were studied to obtain the best modification effect in the experiment. The TNTs were loaded with alendronate and ibuprofen via vacuum drying method and the release properties from the nanotubes were detected in phosphate buffer solution (PBS). The samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and UV-Vis spectrophotometer. The data show that copper is successfully doped to the nanotube surface by hydrothermal treatment, and the optimum hydrothermal treatment conditions are 200°C, 0.5h. The drug loading capacity of the modified sample increased obviously, whether it was hydrophilic or hydrophobic. Meanwhile, the modified nanotubes release more slowly in the later stage. This approach provides an alternative to tailor the surface of TNTs and offer considerable propects for diverse biomedical applications.

Abstract: An experimental investigation was performed to study the wear of a promising dental ceramic, i.e., machinable lithium disilicate glass ceramic, under lubrication conditions, in particular, to examine effects of the surface finish and applied load on wear. Our previous work has shown that a fine finish in a dry condition did not necessarily translate to the lowest wear volume due to changes in the dominant wear mechanisms. This study tested the ceramic specimens with four average surface roughness values of S_a = 143 nm, 217 nm, 353 nm, and 692 nm on a reciprocating sliding friction rig against alumina balls with two applied forces of 5 N and 25 N in a bath of distilled water. Comparing with the results obtained in the dry conditions, this study shows that surface roughness of approximately 200 nm may be suitable for surface preparation of crowns made from the material in the wet and dry wear conditions in the oral environment.

Abstract: The comfort of a workspace for some people is a thing which is not negotiable. It is believed to raise the motivation of people who work in it. A room which is too hot or too cold may cause people working in it unable to concentrate in a manner that their work performance will not be optimal or will cause some of their work delayed and eventually lead to the depression of the workers themselves. From an economic standpoint, this analysis is important because the greater the capacity of the air conditioning system, the greater the power consumption. The purpose of this study is to determine the amount of heat, which is caused by external and internal factors, that arise in the Engineering building at Engineering Academy of Soroako, and to determine the proper capacity of air conditioners which should be installed in the building. To determine the amount of air conditioning capacity needed in the building, an analysis of the cooling load that occurs in the building is necessary. Geographical position, direction of the wall, and building materials are very influential in the absorption of heat from the outside, while the activities of the occupants, lighting loads, and loads of other electrical equipment affects the amount of heat that arise. CLTD / CLF / SCL methods are used in the calculation, and the data required is measured at the peak of the dry season, which occurs in October. Our analysis and calculations obtained that, according to its function, the number of lamps needed in the building are 26 type PL lamps with a power of 23 watts per lamp. The conduction heat gains and maximum daily infiltration occurred at 2pm with a value of 7.51 kW and 1.98 kW, respectively, while the internal heat gains and maximum daily radiation occurred at 3pm with a value of 1.94 kW and 15.41 kW, respectively. It is concluded that the total maximum daily heat gains that arises is 26.50 kW so the capacity of the air conditioner needed is 6.61 kW or rounded to 8.9 PK.