Response-spectrum-based design method for gain-scheduling control of active base-isolated structures with nonlinear viscous dampers

Centrifugal pump is widely used in various fields of the national economy. Pumps, of which 70% are centrifugal pumps, consume 20.9% of the total electricity generation nationwide in China in 2009, according to the statistics. In this paper, the research advances in design methods and characteristics of internal flow fields for centrifugal pumps, carried out by the Research Center of Fluid Machinery Engineering and Technology of Jiangsu University, is introduced. First of all, the Greater Flow Design method, Non-Overload Design method and Splitter Blade Offset Design method are fully discussed through systematically studies. In addition, three methods of performance prediction for centrifugal pumps are adopted, and a CAD/CFD software for hydraulic design and analysis is initially developed. Secondly, to deepen the understanding of characteristics of internal flow in centrifugal pumps, the numerical simulation and PIV measurement investigation have been done. Then the unsteady flow induced vibration and noise are studied considering fluid-structure interaction and fluid-sound interaction. The control of the unsteady flow in centrifugal pumps is also attempted to optimize the design method for centrifugal pumps. In addition, the pressure pulsation and vibration behaviors under both cavitation and non-cavitation conditions are obtained and analyzed. Finally, some detecting methods and criterion for cavitation incipiency and development are put forward.

Evaluation of the microscale structure and performance of asphalt mixtures under different design methods

Stress-laminated timber (SLT) bridge decks are generally designed using either linear hand calculation methods or linear finite-element models. Several studies have shown, however, that the behavior of SLT decks is nonlinear when loaded until failure. In this paper, several linear design methods are compared with one another and with an ultimate load test of a full-scale SLT deck subjected to an eccentric load. Some of the linear hand calculation methods show significant discrepancies in results, depending on the load position. There are also variations in the results from finite-element models, depending on the material properties assigned to the deck. All the design methods failed to predict the deflection of the tested deck when loaded to failure. A larger deflection was observed in the full-scale test than that predicted by the design methods. As a result, the linear design method could underestimate the bending stresses in the deck. Several hand calculation methods are also unable to calculate the transverse forces and moments necessary for design according to Eurocode 5.

In this paper, we propose an efficient design method for a thermal camera with continuous zoom based on the research and manufacturing experience of the thermal camera. In addition, it is divided into system design method, optical design method, mechanical design method, and electronic design method. First, we propose an effective NUC compensation method and a lens-specific sensitivity design method in terms of system. Second, we propose a zoom trajectory design method considering the temperature effect on the optical aspect. Third, it suggests the minimization of optical axis shaking between magnification conversion in terms of mechanism. Finally, we propose a lens-specific temperature compensation method and a speed conversion algorithm according to the zoom interval as an electronic aspect.

Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea

Design method for axially compressed H-sectional aluminium alloy slender column based on CSM

The commonly used TMD design method in the project assumes the TMD has pure linearity. However, in real engineering TMD will exhibit nonlinear behaviors. Without considering the nonlinearity of TMD, the control effect of the TMD that is designed by the linear design method, may be worse and even enlarge the structural response. In this paper, based on the previous study results of nonlinear TMD, the improved design method for engineering application is proposed. The linear design method and the improved design method are compared. Taking the best parameter obtained by the improved design method is less than or equal to 90% of that obtained by the original design method as the dividing line. The critical nonlinear coefficient, reaching which value the improved design method needs to be used, is given. Finally, numerical simulations on two engineering examples are conducted to proof the results.

Land leveling or land grading of surface irrigated fields improve irrigation water distribution and application efficiencies, conserve water and increases crop productivity. Land formation for irrigation face many constraints (ensuring proper slopes, prevention of flood, ensuring canal water command over the field, optimizing earthwork, minimizing truck travel distances, proper equipment utilization). Design engineers traditionally, perform site formation design manually by plane shape, least squire or linear programming methods. Such methods are with different characteristics. The main objective this study is to select and compare performance of these three design methods for proper land leveling design. Consequently, the basic theory of these alternative design methods are reviewed and their performance using data surveyed from five fields in Khartoum North-Sudan, each with different soil surface topographic configurations, is analyzed. The statistical analysis revealed that the linear programming method is the most appropriate design method. Employing the linear programming design method revealed that design slopes in row and cross row directions are within the acceptable range (0.1 to 0.5, the ratio of Cut/fill volumes is within the recommended range (1.1 to 1.3), uniformity of distribution of design elevations of grid points are acceptable and within the target limits (80%), while their deviation is at 80% of grid points around the mean before leveling.

The design of p-cycles in WDM mesh networks has been extensively studied. However, most of studies only deal with a single link failure rather than node failure. In this paper, we develop a new scalable and efficient design method for computing node-protecting p-cycles. The performance of our new proposed design method makes an obvious improvement 20% in capacity redundancy over that of the previous design method. The conventional design methods formulate the problem of pcycle design as an Integer Linear Program (ILP). To solve the ILP, the prerequisite is to a priori enumerated all possible pcycle candidates. For a large network, the resulting ILP maybe intractable as the huge number of cycles may exist. We propose a new design and solution method based on large scale optimization tools, namely Column Generation (CG), where pcycles are generated on-line when needed. The main advantage of our CG-based method is that no p-cycles are a-priori off-line enumerated, the generation of the promising set of p-cycles is embedded in the optimization process. Extensive experiments on several network instances have been conducted for comparison. Experimental results show that our new proposed methods outperforms the previous method in terms of capacity efficiency.

Asphalt treated base (ATB) materials have shown good road performance. There are some differences in the mix design methods used for ATB and Asphalt Concrete (AC) and this paper investigates four different design methods for ATB. Each design method is analyzed by using volume and mechanical indexes, and pavement performance. Based on this analysis, the proper design method of ATB is proposed. 1. ATB Design Method This paper describes the comparison of experimental data with specification criteria recommend in the SUPERPAVE method, the Bailey method, and a mechanical method. The analysis includes determining the effect of different design methods on asphalt pavement performance.

An efficient technique of designing spatial matrix filter for array signal preprocessing based on convex programming was proposed. Five methods were considered for designing the filter. In design method 1, we minimized the passband fidelity subject to the controlled overall stopband attenuation level. In design method 2, the objective function and the constraint in the design method 1 were reversed. In design method 3, the optimal matrix filter which has the general mean square error was considered. In design method 4, the left stopband and the right stopband were constrained with specific attenuation level each, and the minimized passband fidelity was received. In design method 5, the optimization objective function was the sum of the left stopband and the right stopband attenuation levels with the weighting factors 1 andγ, respectively, and the passband fidelity was the constraints. The optimal solution of the optimizations above was derived by the Lagrange multiplier theory. The relations between the optimal solutions were analyzed. The generalized singular value decomposition was introduced to simplify the optimal solution of design methods 1 and 2 and enhanced the efficiency of solving the Lagrange multipliers. By simulations, it could be found that the proposed method was effective for designing the spatial matrix filter.

Design method for relief well trajectory to avoid side-track operations and control the relative distance

This paper describes how gain scheduling control is applied to a continuous stirred tank reactor model. The CSTR process, equipped with a cooling system, is modelled. Based on the resulting nonlinear model, a gain scheduling controller is designed. The gain scheduling follows a scheme denoted bias compensation. Compared to earlier reported gain scheduling schemes, the proposed scheme results in a controller that is less complex, which is advantageous in the controller implementation stage. Numerous simulations are performed, using the gain scheduling controller and two choices of control input to the reactor model. The simulation results indicate that a gain scheduling controller performs better than a linear controller. Simulations using different choices of control input to the reactor model indicate that proper process design is crucial for the controlled process performance.

The design methods of axial flow fan mainly include free vortex design method and random vortex design method. The random vortex design method and free vortex design method were used to design aerodynamic parameters of two fan systems, and then the performance of these two fan systems was compared by numerical simulation. In the numerical simulation, the random vortex method and free vortex method are applied, respectively, based on the fan design parameters given by the acoustically guided wind tunnel fan section, and the physical model was established, the numerical simulation comparison study was conducted for the two sets of fan systems. The comparative analysis of the numerical simulation results shows that compared with the free vortex method, the fan designed by the random vortex method can reduce the local separation of tip and root of the blade, and the axial velocity distribution of fan blade and fan section outlet can be more uniform, and there is a certain increase in fan blade efficiency. These results verify that the design method of random vortex fan is feasible in large wind tunnels, especially in wind tunnels with aerodynamic noise reduction requirements, and can provide powerful conditions for optimizing aerodynamic and acoustic performance of the fan.

Structural behaviour of cold-formed thin-walled short steel channel columns at elevated temperatures. Part 2: Design calculations and numerical analysis