Minimum Construction Cost Research Articles

Optimization of shape and functional structure of buildings as well as heat source utilisation. Partial problems solution

The aim of the paper is to present rational methods of multicriteria optimization of the shape and structure of energy-saving buildings, as well as optimization of heat sources taking into account the energy criteria. Mathematical model describing heat losses and gains in a building during the heating season was selected and refined. It takes into consideration heat losses through walls, roof, floor and transparent partitions as well as heat gains due to insolation across transparent partitions. Particular attention was paid to a more detailed description of heat gains due to solar radiation, depending on the position of partitions relative to their north–south axis and the degree of their use. The problem of multicriteria optimization of individual homes and blocks of flats was formulated on the basis of the following criteria: • minimum construction costs, including cost of materials, erection, heating installations together with the cost of heat sources, • minimum seasonal demand of heating energy, • minimum of pollution emitted by heat sources installed in the building. The following were accepted as the global optimization criteria allowing to find the preferred solution: • minimum building construction costs and its running costs over N-years’ period together with minimum environment pollution during that period, • minimum distance from the point belonging to the compromise set to the ideal point. The method of solving the above formulated problem consists in decomposing it into three part-problems: • optimization of internal partitions of the building, • optimization of the shape of building, • optimization of heat sources. Part-problems must be co-ordinated subsequently.

A module-oriented tool for optimum design of stiffened structures—Part I

The development of the LBR-5 “Stiffened Panels Software” is included in the development of a new design methodology to ease and to improve preliminary studies of naval structures and floating hydraulic structures. The ultimate target is to link standard design tools (steel structure CAD, hull form, hydrostatic curves, floating stability, weight estimation, etc.) with a rational optimization design module and a minimum construction cost (or minimum weight) objective function. This paper is the first part of a series of two articles. It focuses on the ‘ Module-Oriented Optimization’ methodology and on the rational constraints. The second paper presents the optimization technique using convex linearization and a dual approach, and the optimization of an FSO unit as an example (Rigo and Fleury, Marine Stuructures, 2001). LBR-5 allows, as of the first draft, an optimization of the scantling of the structure's constituent elements. Relevant limit states of the structure are taken into account thanks to a 3D rational analysis of the structure based on the general rules of solid-mechanics and structure behaviour. The optimization module is composed of 3 basic modules (OPTI, CONSTRAINT and COST) and a group of sub-modules (in external databases). Among these the user selects a set of relevant sub-modules (i.e. geometrical and structural constraints). Since the present optimization deals with least construction costs (as objective function), and uses an explicit objective function (not empirical), the user must specify labor costs (unitary material costs, welding, cutting, etc.).

Scantling optimization based on convex linearizations and a dual approach—Part II

The development of the LBR-5 “Stiffened Panels Software” is included in the development of a new design methodology to ease and to improve preliminary studies of naval structures and floating hydraulic structures. It allows, as of the first draft, an optimization of the scantling of the structure's constituent elements. The ultimate target is to link standard design tools (steel structure CAD, hull form, hydrostatic curves, floating stability, weight estimation, etc.) with a rational optimization design module and a minimum construction cost (or minimum weight) objective function. It is developed to be a user-oriented tool. The optimization module is composed of three basic modules (OPTI, CONSTRAINT and COST) and a group of sub-modules (in external databases). Among these the user selects a set of relevant sub-modules (i.e. geometrical and structural constraints). Since the present optimization deals with least construction costs (as objective function), and uses an explicit objective function (not empirical), the user must specify labor costs (unitary material costs, welding, cutting, etc.). This paper is the second part of a series of two articles. The previous paper focused on the ‘Module-Oriented Optimization’ methodology and on the rational constraints (Rigo, Marine Structures 2001). This paper presents the optimization algorithm based on convex linearization and a dual approach (OPTI module). It also includes the optimization of a FSO unit as a detailed example.

Automating utility route design and planning through GIS

In trench construction, one of the tasks for engineers is to select a suitable route to minimize construction cost and obstructions. This paper discusses the development of a Geographic Information Systems (GIS)-based system to automate the process of routing and design of an underground power supply system. In the system, surface and underground utilities are represented in several coverages. Using network analysis, the system determines the optimal paths for routing the utilities. Through database queries and spatial operations, the construction conflict points between the basic coverages and the selected route are not only identified, but a reallocation schedule is also determined.

Scheduling/Cost Optimization and Neural Dynamics Model for Construction

A general mathematical formulation is presented for scheduling of construction projects and applied to the problem of highway construction scheduling. Repetitive and nonrepetitive tasks, work continuity constraints, multiple-crew strategies, and the effects of varying job conditions on the performance of a crew can be modeled. An optimization formulation is presented for the construction project scheduling problem with the goal of minimizing the direct construction cost. The nonlinear optimization is then solved by the neural dynamics model developed recently by Adeli and Park. For any given construction duration, the model yields at the optimum construction schedule for minimum construction cost automatically. By varying the construction duration, one can solve the cost-duration trade-off problem and obtain the global optimum schedule and the corresponding minimum construction cost. The new construction scheduling model provides the capabilities of both the CPM and LSM approaches. In addition, it provides features desirable for repetitive projects such as highway construction and allows schedulers greater flexibility. It is particularly suitable for studying the effects of change order on the construction cost. This research provides the mathematical foundation for development of a new generation of more general, flexible, and accurate construction scheduling systems.

Increase of the efficiency of operating the cascade of Vakhsh hydroelectric stations by using part of the runoff of the Pyandzh River

1. In connection with the historically established economic conditions and existing agreements with neighboring countries, the cascade of Vakhsh hydrostation was designed on the basis of operating conditions in an irrigation regime and cannot provide Tajikistan's own need for power in the winter, the deficit of which is 4 billion kWh/yr. The traditional methods of solving this problem call for the construction of either an irrigation reregulator in the lower course of the river or a hydrostation operating in a power compensator regime in its upper course. Both these variants require vast expenditures of material and financial resources and provide an effect just due to one particular hydro development. 2. The natural conditions of Tajikistan created the unique possibility of increasing the effectiveness of the combined operation of the Vakhsh cascade by constructing a tunnel conduit and using the runoff of the Pyandzh River in operating the Vakhsh hydrostations. With minimum construction costs the power effect of the cascade in this case increases substantially since it is achieved due to the repeated use of Pyandzh River water at all stations of the cascade and without any detriment for irrigation. 3. Realization of the proposed project will increase the total power production of the cascade for all hydrostations specified by the scheme depending on the degree of streamflow regulation by the Pyandzh reservoir. The cost effectiveness of the proposed project is an order higher than that of the traditional variants. Even for the stations operating today on the cascade its effect is comparable to the effect of the Nurek hydrostation with respect to all indices. Here the total cost of the tunnel conduit together with the dam is an order lower than the cost of the Nurek hydro development.

The network synthesis problem in a cycle

The network synthesis problem is to design an undirected network with a minimum total construction cost which non-simultaneously satisfies given flow requirements between pairs of nodes. This well-known problem was introduced by Gomory and Hu (1961) who formulated it as a very large linear program and solved it by a method similar to column generation. We provide an efficient algorithm for this problem when the underlying graph is a cycle.

ROADPLAN: A Tool for Designing Forest Road Networks

The ROADPLAN model produces a road network plan for a forest area that is being accessed for the first time. It is based on a raster geographic information system (GIS), for each cell of which the harvesting priority (based on available merchantable volume) is known and the cost of road construction can be estimated. Wood transportation cost ($/ m3.km) is assumed to be constant. All potential cutblocks, taking into account specified volume and area constraints, are first identified. For each cutblock, the cost of constructing potential road links to all points on the existing network and the cost of transporting wood over each link and along the network to one of the access points to the area are calculated. At every step the cutblock with the minimum combined construction and transportation cost (in $/rrf) is added to the network. The model was developed and tested on data from a simulated forest, and then further evaluated on a 100000 ha forest block in northern Ontario where it was found to produce realistic networks similar to that planned for the area. Compared with existing models, ROADPLAN permits considerable flexibility in generating the road network.

Model to Estimate Highway Earthwork Cost in Nepal

In a developing country like Nepal, where in most cases projects are externally financed, the minimization of construction costs is the most important factor in a highway project. But the cost estimates to be used at the earliest stage of design, where only a limited data are available in primitive conditions, have usually been based on lump-sum costs derived from historic data that have to be transformed before they can be used satisfactorily. An equation to estimate the earthwork cost in a highway project in Nepal was hence analyzed, and it could be used for the cases in Nepal at the route location stage. The basic input data required were the general topographical information of the area concerned in terms of topographical contoured maps and the possible horizontal alignments. The results obtained from the equation were satisfactory for estimating the earthwork cost.

Theoretical study for the optimum intensity and diffraction efficiency response for echelle reflection grating in the microwave region

The optimum intensity response and the diffraction efficiency for a microwave echelle reflection grating depends upon the judicious selection of its geometrical parameters for a particular wavelength. The matter was studied thoroughly from a theoretical standpoint and it appeared that the suitable choice of geometrical parameters could be made from contour plots of 3D-intensity curves. The method yields valuable information for the optimisation of intensity as well as the diffraction efficiency with minimum construction cost.

The Scaling of Root Anchorage

The scaling of three anchorage systems, the fibrous systems of climbing plants and the tap and plate systems found in self-supporting plants, has been investigated. Optimal shapes for both fibrous and tap-root systems are identified; shapes which provide maximum anchorage for a minimum construction cost. To ensure a constant factor of safety against anchorage failure the linear dimensions of each of these anchorage systems must scale with stem radius.Optimal shapes for plate systems cannot readily be determined; however, their efficiency will rise with plant size because the anchorage provided by the weight of the root—soil plate increases faster than stem strength. As plants get larger, therefore, plate systems become relatively cheaper to construct. This may be one reason why tree saplings have tap-root systems but develop plate systems as they grow.The investment plants must make to anchorage systems will depend on the manner in which the shoot system scales. With isometric scaling of the stem the relative investment in anchorage will remain constant. With the additive scaling possible in climbing plants, large plants having relatively thinner stems than small ones, anchorage investment will fall. If elastic similarity is maintained, larger plants having relatively thicker stems, the relative investment in anchorage must rise.

Compact Treatment Plant Layout

One of the last steps in the preliminary design of a treatment plant is to develop the plant layout. By this stage of the design process, the site has been selected, the treatment processes have been identified, and the approximate dimensions of the process units have normally been established. The engineer then must arrange the process units on the site. There are a number of alternative basic plant layouts. The particular plant layout selected can have a significant effect on construction cost, hydraulics, plant performance, operation and maintenance (O&M), and ease of expansion. This article describes a compact plant layout that simplifies O&M and minimizes construction cost.

The Mechanics of Anchorage in WheatTriticum aestivumL.: I. THE ANCHORAGE OF WHEAT SEEDLINGS

Model of the mechanics of uprooting lead to the identification of ‘optimal’ anchorage systems which can withstand a given upward force at a minimum construction cost. Such systems have many downward-pointing fibrous roots which are strengthened progressively towards the base. A study of the anchorage system of 7- and 21-d-old wheat (Triticum aestivum L.) plants showed that the plants possessed five seminal roots, of which only three pointed vertically. Each root was well suited for anchorage, being convered in root hairs and strengthened progressively towards the base by lignification of the stele. Strength and stiffiness of roots but not their mass per unit length increased with age. There was little interaction between roots when plants were uprooted; the three vertical roots broke while the two horizontal ones pulled out, as occurred when roots were pulled out singly, Uprooting forces increased with age and the root system could withstand uprooting forces greater than those required to pull out upper leaves, so reducing the chances of the plant being uprooted by a herbivore, By 3 weeks a stiff adventitious root system, which would later help prevent the wheat lodging, was developing.

A Study of an Expert System for Optimum Structural Design of a Cylindrical Shell Type Submersible

An object-oriented expert system, aiding in the structural design of semi-submersibles, particularly those constructed with ring-stiffened shells subjected to external pressure, is studied in this paper. A ring-stiffened shell must have enough structural strength to avoid collapse. On the other hand, there are some requirements such as minimal weight and minimal construction cost. Since the two abovementioned requirements are mutually opposing, an optimal design technique must be considered. In this study, a sensitivity analysis is implemented inside of the expert system to achieve an optimal design.The developed expert system is basically written in Uti-LISP and implemented on an EWS-A ring-stiffened shell is designed by this system using the same requirements that were used in the design of an actual submersible. Total constructon cost and weight of the submersible designed by this expert system and that of the real submersible are compared here.

Ignition and reactor application of deuterium based fuel cycles in field reversed configurations

Self-consistent plasma modelling, on the assumption that all particle species have the same confinement time, is applied to a field reversed configuration (FRC) to show that plausible designs of an ignited advanced fuel reactor are possible within the framework of present day technology. FRCs in the ⟨β⟩ ∼ 1 state are predicted to be microscopically and macroscopically stable; here, any ignited state must be of this kind since the plasma is heated up by a vast amount of nuclear power which even exceeds the electric output. In the ⟨β⟩ ∼ 1 state, the steep pressure gradient appears to concentrate dissipation into a thin sheath formed on the plasma surface; hence, the problem can be solved independently of the detailed local dissipative properties, in analogy to the case of a supersonic flow decelerated through an Hugoniot adiabatic shock. It was found out that, in the ignited state, self-pinching of the electrons takes place in the scrape-off layer towards the X-point so that the size of the loss hole from the scrape-off layer is reduced, which raises the edge plasma pressure to a high level; thereby, serious impurity concentration is eliminated. In the paper, possible D-based steady state fuel cycles are studied systematically by using a formulation which predicts each important parameter of a simple toroidal FRC reactor if only the electric power output and the plasma radius are specified. In optimizing the burning temperature, care was taken to satisfy the criteria for thermal stability. A study has also been pursued on a complex closed reactor system which is fed by D alone and exhausts the final fusion products only. It is found that flexible design is possible for such a complex system to minimize construction cost or environmental effects. Advanced fuel reactors are demonstrated to be very compact in size so that a field strength and a plasma volume approximately equal to those of JT-60 may be sufficient for a fusion reactor constituting the basis of a 1000 MW(e) power plant

Recursive Optimization for Seismic Steel Frames

The theoretical derivations and numerical procedures used in the computer program ODSEWS‐2D‐II for the analysis and optimum design of two‐dimensional regular and irregular steel frames subjected to static, earthquake, and wind forces are presented. The seismic input can be interacting ground motions of actual earthquake records, various response spectra, and different building provisions of the Uniform Building Code (UBC), ATC‐03 in the United States, and TJ‐11 in China. Included are the mathematical formulation based on the consistent mass and the displacement method with consideration of geometric nonlinearity, three levels of recursive optimization procedures, the objective function of minimum construction and damage costs, and the constraints of stresses, displacements, frequencies as well as the upper and lower bounds of the design variables. Several design examples are provided to show the efficiency of the proposed algorithms, the versatility of the computer program, and the effect of the various code requirements on the optimum solutions.

The segmentation of hadron calorimeters

Optimization of the segmentation of large hadron calorimeters is important in order to obtain good resolution for jet physics at minimum construction cost for the next generation of high energy experiments. The principles of the segmentation of hadron calorimeters are discussed. As an example, the Monte Carlo optimization of the segmentation of the L3 hadron calorimeter barrel at CERN is described. Comparisons of results for the reconstructed jet shapes show that the optimum number ADC channels is about 20K for the readout of 450K wires of the proportional chambers. The matching between the sandwiched φ towers and Z towers is the dominant factor for angular resolution. Based on these Monte Carlo simulations, an optimized tower structure is obtained.

Activated Sludge Settlers: Design and Optimization

Activated sludge settlers perform two functions simultaneously: clarification and sludge thickening. Depending on the values of the mixed liquor and return sludge concentrations and on the sludge settling characteristics either one of these functions may limit the solids loading rate that can be applied to the settler, which in turn determines the required settler surface area. A method is developed to establish which of the two functions is determinant for the maximum solids loading rate in a particular design situation. Expressions are derived to calculate the required settler surface area for clarification and for thickening. These expressions are based on the experimentally verfied supposition that the zone settling velocity decreases exponentially with increasing suspended solids concentration. A graphical method to determine the optimal mixed liquor and return sludge concentrations for minimum construction and operational cost is presented.

Hematoporphyrin-derivative optical-fluorescence-detection instrument for localization of bladder and bronchous carcinoma i n s i t u

The use of hematoporphyrin derivative (HpD), a drug which concentrates in cancer cells, causes a cytotoxic effect on these cells when irradiated with the appropriate wavelength of light. The HpD will fluoresce at a wavelength of 630 nm when excited by 405-nm light. Instruments which are able to cause and detect this fluorescence will assist the surgeon to locate regions of neoplasms which contain HpD. Once the neoplastic region is located, the surgeon can treat this region destroying the neoplastic cells. The recent construction and successful operation of a photodetection instrument for the localization of early carcinoma in situ of the bladder and bronchous in humans is discussed. This instrument is in some ways similar to previously described devices with major improvements due to the use of available electro-optical equipment and elimination of the need for modification or manufacture of special surgical ‘‘scopes,’’ thereby minimizing construction costs.

A contribution to the methods of optimizing the spotting of transmission line towers

An exact method for the choice of types, heights and sites of towers along a transmission line route, enabling the determination of the absolute minimum construction cost, is described. On the basis of a simplified method, sources of inaccuracies in the existing approach to the problem are analysed and an original procedure of designing tower spotting, in the neighbourhood of major objects to be crossed by the line, is presented. The task of this procedure is to find the optimum number and parameters of the spans which form the crossing section with an increased degree of security. In the case of both methods the solution is obtained by the use of dynamic programming on a digital computer. Some results of the calculations carried out for a fragment of 220 kV transmission line are given.