Design and Construction of a Dual Axis Passive Solar Tracker, for Use on Yucata´n

2011 ◽  
Author(s):  
Mari´a M. Pe´rez Sa´nchez ◽  
David Balam Tamayo ◽  
Ricardo H. Cruz Estrada
Keyword(s):  
Degrees Of Freedom ◽  
Operating Conditions ◽  
The Sun ◽  
Pv Panel ◽  
Solar Tracker ◽  
Passive Solar ◽  
The Cost ◽  
Economical Alternative ◽  
Critical Aspects

In this investigation, we propose to use the thermal expansion properties of metals in a bimetallic strip as a base of operation of a passive solar tracker. The design process involved the determination of all aspects necessary to make a first prototype based on requirements and operating conditions previously identified. Predictive mathematical models were used to decide critical aspects. Certainly, some aspects of the design were determined experimentally to ensure the proper functioning of the solar tracker. The product of this research was the construction of a prototype with the ability to be placed with an average angular difference of 25 degrees to the position of the sun, under controlled conditions. The device created is a passive solar tracker with two degrees of freedom, one used to track the sun daily, operates automatically actuated by the bimetallic strip, the other one is manually adjusted in seasonal changes to compensate the variation in the decline of the sun along the year. Although the accuracy of the system is low, the cost of production is well below the purchase price of any commercial solar tracker, and its construction is simple, making it an economical alternative to increase the production of photovoltaic energy on a PV panel currently fixed.

Parametric Optimization of Structures Under Combined Base Motion Direct Forces and Static Loading

1998 ◽  
Vol 124 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Izhak Bucher
Keyword(s):  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Operating Conditions ◽  
Design Parameters ◽  
Power Spectral ◽  
Loading Patterns ◽  
The Cost ◽  
Selection Of ◽  
Eigenvectors And Eigenvalues

This paper deals with the optimization of vibrating structures as a mean for minimizing unwanted vibration. Presented in this work is a method for automatic determination of a set of preselected design parameters affecting the geometrical layout or shape of the structure. The parameters are selected to minimize the dynamic response to external forcing or base motion. The presented method adjusts the structural parameters by solving an optimization problem in which the constraints are dictated by engineering considerations. Several constraints are defined so that the static deflection, the stress levels and the total weight of the structure are kept within bounds. The dynamic loading acting upon the structure is described in this work by its power spectral density, with this representation the structure can be tailored to specific operating conditions. The uncertain nature of the excitation is overcome by combining all possible spectra into one PSD encompassing all possible loading patterns. An important feature of the presented method is its numerical efficiency. This feature is essential for any reasonably sized problem as such problems are usually described by thousands of degrees of freedom arising from a finite-element idealization of the structure. In this paper, efficient, closed form expressions, for the cost function and its gradients are derived. Those are computed with a partial set of eigenvectors and eigenvalues thus increasing the efficiency further. Several numerical examples are presented where both shape optimization and the selection of discrete components are illustrated.

scholarly journals Mathematical model for optimizing the fleet of vehicles for performing land reclamation works

2021 ◽  
Vol 274 ◽  
pp. 11004
Author(s):  
Talgat Gabdullin ◽  
Marat Makhmutov
Keyword(s):  
Land Reclamation ◽  
Physical Nature ◽  
Operating Conditions ◽  
Special Equipment ◽  
Technological Complex ◽  
Reliability Characteristics ◽  
Fundamental Possibility ◽  
Group Form ◽  
The Cost

When choosing technical means for performing various technological processes and, in particular, for carrying out reclamation and cultural-technical works, two aspects should be taken into account: the fundamental possibility of using machines and the level of their reliability. But if the choice of technical means according to the fundamental possibility of use for performing a specific operation is sufficiently developed («Systems of machines», catalogs of special equipment have been developed), then the choice of means of repair and technical impact, depending on quantitative data and qualitative characteristics of reliability, is currently not fully studied. This is due to the lack of a sufficient database on malfunctions of the specified technical means and, as a consequence, the lack of reliable indicators of their reliability. Analysis of the data on the operation of technical means in land reclamation and construction organizations shows that due to the low reliability of machines, up to 40% of the cost of their work is the cost of maintenance and repair, while the share of time resources for downtime for technical reasons in the total fund of the working time reaches 40-50%. It should be noted that this is only part of the damage caused by the lack of reliability of the machines. Improving the methods of using machines led to the creation of mechanized complexes - a group form of machine work. Therefore, due to the widespread use of complex mechanization in land reclamation construction, the stop of one machine of a technological complex leads to a stop of the entire technological process. Thus, the determination of the reliability characteristics of the units of technological complexes, namely, the establishment of the physical nature, failures, the identification of the causes of their occurrence, as well as the determination of the need for repair and technical actions, will provide the necessary operational and economic performance indicators of the entire technological complex in specific operating conditions. In this regard, the issue of determining the optimal provision of repair and technical impacts on the units of technological complexes, taking into account their components, is an urgent task that requires separate research.

scholarly journals Using Simplified Models to Assist Fault Detection and Diagnosis in Large Hydrogenerators

2017 ◽  
Vol 2017 ◽  
pp. 1-18
Author(s):  
Geraldo Carvalho Brito Junior ◽  
Roberto Dalledone Machado ◽  
Anselmo Chaves Neto
Keyword(s):  
Degrees Of Freedom ◽  
Thickness Distribution ◽  
Accurate Determination ◽  
Fault Detection And Diagnosis ◽  
Operating Conditions ◽  
Vibration Monitoring ◽  
Simplified Models ◽  
Detection And Diagnosis ◽  
Hydrodynamic Effects

Based on experimental evidence collected in a set of twenty 700 MW hydrogenerators, this article shows that the operating conditions of large hydrogenerators journal bearings may have unpredictable and significant changes, without apparent reasons. These changes prevent the accurate determination of bearing dynamic coefficients and make the prediction of these machines dynamic behavior unfeasible, even using refined models. This makes it difficult to differentiate the normal changes in hydrogenerators dynamics from the changes created by a fault event. To overcome such difficulty, this article proposes a back-to-basics step, the using of simplified mathematical models to assist hydrogenerators vibration monitoring and exemplifies this proposal by modeling a 700 MW hydrogenerator. A first model estimates the influence of changes in bearing operating conditions in the bearing stiffnesses, considering only the hydrodynamic effects of an isoviscous oil film with linear thickness distribution. A second model simulates hydrogenerators dynamics using only 10 degrees of freedom, giving the monitored vibrations as outputs, under normal operating conditions or in the presence of a fault. This article shows that simplified models may give satisfactory results when bearing operating conditions are properly determined, results comparable to those obtained by more refined models or by measurements in the modeled hydrogenerator.

scholarly journals Determination of the features and effectiveness of the pivot sprinkler with corner irrigation system

2020 ◽  
Author(s):  
O. Mitrofanov ◽  
◽  
V. Sidorenko ◽  
S. Sidorenko
Keyword(s):  
Capital Investment ◽  
Irrigation System ◽  
Operating Conditions ◽  
Theoretical Research ◽  
Irrigated Agriculture ◽  
Irrigation Systems ◽  
Term Operation ◽  
Irrigated Area ◽  
The Cost

Introduction. Circular-action sprinklers, as shown by the practice of their long-term operation and previous studies, have significant advantages over front-end machines: maintenance is minimized, the ability to fully automate irrigation processes and network power supply, a one-hydrant water supply system, etc. At the same time, pivot irrigation leaves the corner sections of the field without irrigation, which account for up to 20% of its area - and this is a significant drawback of pivot irrigation machines. Foreign manufacturers of irrigation machines produce and sell additional swivel fenders for pivots that irrigate the corners of the field. They are also called "corner irrigation systems". Since 2018, such systems began to appear in Ukraine. Specialists of the South-Ukrainian branch of L. Pogorilyy UkrNDIPVT investigated the corner irrigation system of the company "Valley" by testing in the conditions of economic operation. Research goal. Determination of parameters and characteristics of the corner irrigation system "V-Flex Corner Valley", assessment of its effectiveness and prospects for widespread implementation. Research methods. Theoretical research was carried out by analyzing the studied information resources. Laboratory and field studies were carried out by testing the irrigation system under operating conditions. System parameters and characteristics were determined according to standardized methods. Results. The design features and principles of the irrigation system functioning have been investigated and described. The tests determined the main operational characteristics of the irrigation system in comparison with the characteristics of the pivot sprinkler (using materials from previous studies). The economic indicators of the irrigation system and the circular machine are determined in comparison. The factors of increasing/decreasing efficiency and their quantitative indicators have been investigated. The analysis of the results obtained and the reasons that hinder the widespread introduction of corner irrigation systems into the practice of irrigated agriculture in Ukraine are identified. Сonclusions. Tests and studies of the pivot sprinkler with corner irrigation system have proven the functional excellence and high operational reliability of the irrigation system. The use of a corner irrigation system made it possible to increase the irrigated area by 21.86 % without changing the basic infrastructure and borders of the irrigated field. Implementing a corner irrigation system requires significant capital investment: the cost of a corner wing, which irrigates 21.86 % of the field, is 79 % of the cost of a basic pivot, which irrigates 59.72 % of the field.. The increase in gross income due to an increase in the irrigated area provides a basis for predicting the return on investment when growing highly profitable crops.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

Mekanisme Dan Proteksi Jaminan Nasabah Pada Gadai Informal

Liquidity ◽  
2017 ◽  
Vol 6 (2) ◽  
pp. 103-109
Author(s):  
Yuri Nanda Larasati ◽  
Jafril Khalil
Keyword(s):  
Qualitative Research ◽  
Research Methods ◽  
Financial Services ◽  
Field Data ◽  
Qualitative Research Methods ◽  
Research Field ◽  
Consumer Society ◽  
Library Research ◽  
The Cost

Regulation of the financial services authority (OJK) No. 31/POJK.05/2016 on Venture had arranged that the financial services agency on the basis of the law of pledge is in coaching and supervision OJK. Yet the existence of laws – invitation to Governing Enterprise pawn shops causing business activities conducted by the above parties are not yet regulated. The condition is feared could cause harm to the consumer society. The purpose of this research is to know the procedures, mechanisms, protection of goods and guarantee the consumer on an informal pledge financing, methods of determination of the cost of maintenance of the goods and the goods of the execution mechanism of the pledge as well as protection for the collateral items are viewed from the side of the consumer by looking at laws-invitations and Sharia. To find out whether the pledge have gotten permission from OJK. This research uses qualitative research methods with the study of library research, field data and simulations. The approach used in this study is the empirical juridical approach. Elaboration upon the results is discussed further in this article.

CAD Of Anticorrosive Protection Of Steel Structures

2019 ◽  
pp. 18-23
Keyword(s):  
Protective Coating ◽  
Computer Aided Design ◽  
Steel Structures ◽  
Cost Effective ◽  
Operating Conditions ◽  
Computational Tool ◽  
Protection Method ◽  
Cost Effective Method ◽  
The Cost ◽  
Aided Design

The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.

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