Equation (1) mathematically represents an idealized form of a McKibbenstylemuscle based on energy balance. A real system has inefficiencies which cause an error in predicted force produced of up to 30% when compared to data generated from Equation (1) . To reduce the error, there are two major ways to adjust the model. The first method uses experimental results from actual muscles to determine coefficients for a desired equation. The second method utilizes additional corrective terms based on the physical properties of the system. These terms are added to Equation (1). This thesis focuses on the second modeling approach. The second method will generate a model which allows for manipulation of the effects of the physical properties of the system. A key benefit of a physical properties model is the ability to run numerical simulations of a muscle’s expected response before construction. A discussion of both methods is included below.
Gain-Bandwidth Product (GBP) is a nonlinear function of the ratio of piezoelectric composite acoustic impedance to load material acoustic impedance. The acoustic impedance of the composite depends on ceramic volume fraction and polymer properties in a piezoelectric composite structure 1 . The higher the impedance mismatch between device and load results in a reduction in terms of device bandwidth and sensitivity, as less energy can be transferred between the device and the load. However, when lowering the ceramic volume fraction to improve impedance matching, the volume of active piezoceramic also reduces which impacts on the electro-mechanical efficiency. The softer the polymer used, the easier it is for the ceramic to expand, because the polymer absorbs lateral contraction of the ceramic pillars as they elongate. However, softer polymer materials have a corresponding higher longitudinal wave damping, which also limits GBP. Additionally, with very soft polymers and high ceramic volume fractions, the polymer surface tends to vibrate in anti-phase, being pushed out by the mechanically stiff ceramic 3 . Similar effects may occur at very low ceramic volume fractions, when the polymer does not bond well to the ceramic pillars and tends to vibrate independently. Accordingly, these effects reduce GBP and may give rise to parasitic surface Lamb waves. Therefore stiffer polymers have to be used at extreme ceramic volume fractions. The impact of material thickness is more straightforward: the thicker the device, the greater the volume of piezoceramic which results in a device with enhanced sensitivity. However, thickness cannot be changed freely because the operational resonant frequency defines the material thickness.
stresses were computed with an FEM: ANSYS program. 13) Two-dimensional axisymmetric model had 46,981 nodes and 15,494 elements by meshing up to element size of 0.1 mm. The type of element used is two-dimensional 8-node plane element (PLANE82). Figure 4 shows element condition, boundary condition, and PLANE82 element conﬁguration that were used to analyze the residual stress. Table 1 lists the materialproperties used to calculate the stress. The material composition is taken to be constant in both the radial and circumferential directions. Table 2 lists the composition, weight of each layer, density, and calculated thicknesses used for numerical analysis of FGM model. The residual stresses were assumed to be generated during cooling stage when sintered temperature of 1700 C
In this paper the screw is modeled as a rotating Euler-Bernoulli beam for longitudinal and torsional vibrations. Table mass is assumed traveling according to a triangular velocity time function. Table inertia is considered as a moving load on the rotating screw. Normal modes of a constrained structure method is used to find dynamic equations of the motion, first three modes of the longitudinal and torsional vibration are considered, table mass vibrations during the travel are studied.
In conclusion, it should be noted that in order to perform accurate dynamic calculations of buildings and structures, taking into account the deformable subsoil, which affects the fluctuations of the entire system, it is necessary to verify the numerical models instrumentally at a similar object or after construction completion of designed structure. Using the three-channel seismic registrar REGISTER is a simple procedure and allows one to check the correctness of the natural frequencies and damping parameters determination if all the necessary geological surveys are performed and the modulus of elastic dynamic deformations is determined. If only standard engineering and geological surveys are available, additional geophysical studies are required using multichannel seismic stations, such as SINUS from the Institute of Geophysics UB of RAS, with 24 one-component geophones.
Abstract. This paper investigates modeling and dynamic behavior of inductively coupled power transfer system with multiple receivers. Firstly, by using the idea of decomposition to set up model of the inductively coupled power transfer system with multiple receivers. Then, by simulation, analyzing dynamic behavior of the inductively coupled power transfer system with two receivers. The proposed modeling method is help to clearly illustrate the dynamic behavior of each subsystem. And results indicate variation of coupling parameters has a significant influence on the dynamic behavior of the system.
The goal of these studies is to determine which parameter values result in the least amount CG movement. This is accomplished by subtracting the maximum from the minimum CG value to compare the range of values in each direction. In the case of the z direction, only values after equilibrium are considered so that the initial settling of the platform to its equilibrium state does not affect results. For each parameter tested, only that parameter will be incrementally modified and all other parameters will be set to their default values, shown in the “parameter.m” code in Appendix A. All tests will be done using the previously described earthquake displacement forcing function to simulate the system responding to a real event.
The damping ratio and the wear rate are highly dependent on the brush material’s properties . For this purpose a further investigation of the brush material was made with hardness tests (Section 1.3) and DSC (Section 1.4). As presented in Section 1.5, the graphite and copper are the main components of the analysed brush. From a previous analysis of copper by DSC measurements it is known that the recrystallization temperature is at 170 ◦ C .
Cellular Automata (CA) is a mathematical tool that has been used for years to describe complex systems. It can be viewed as a simple model of spatially prolonged decentralized system comprised of a number of cells (individual components). The dissemination between these cells is restricted to local interaction. The overall formation can be perceived as a parallel processing device. This
For developing good concrete mix it is important to select proper ingredients, evaluate their properties and understand the interaction amongst the different material. It normally contain not only Ordinary Portland cement, Aggregate, water but also fibrous material and supplementary cementing material. The ingredients used for our project work are: Ordinary Portland cement of 53 grade, coarse aggregate, fine aggregate, water and pozzolanic material like sugarcane bagasse ash (SCBA).
Neuro-Fuzzy Systems (NFS) are computational intelligence tools that have recently been employed in hydrological modeling. In many of the common NFS the learning algorithms used are based on batch learning where all the parameters of the fuzzy system are optimized off-line. Although these models have frequently been used, there is a criticism on such learning process as the number of rules are needed to be predefined by the user. This will reduce the flexibility of the NFS architecture while dealing with different data with different level of complexity. On the other hand, online or local learning evolves through local adjustments in the model as new data is introduced in sequence. In this study, dynamic evolving neural fuzzy inference system (DENFIS) is used in which an evolving, online clustering algorithm called the Evolving Clustering Method (ECM) is implemented. ECM is an online, maximum distance-based clustering method which is able to estimate the number of clusters in a data set and find their current centers in the input space through its fast, one-pass algorithm. The 10-minutes rainfall-runoff time series from a small (23.22 km 2 ) tropical catchment named Sungai Kayu Ara in Selangor, Malaysia, was used in this study. Out of
Abstract: Extensive literature review has been carried out in the field of Composite vibration. This work is concerned with the comparison of experimental and simulation analysis and enhancement of mechanical properties of composite material like (jute abaca glass fiber). The finite Element method has been used computational by means of ANSYS 15.0 a main reason for adopting ANSYS 15.0 is that there is no analytical model has been develop for Composite structure in presence of singularities i.e. total deformation and shear stress. Following analysis has been carried out for dogbane shape structure and we have taken the dimensions & boundary condition from the base paper . (i.e. simply supported shear strength of laminated composite). Keywords: Composite material, Finite element method (FEM), Total deformation, shear stress.
Many companies have realized that reverse logistics is an important competitive and strategic part of their business mission. The usage of reverse logistics in the business sector is increased due to the implementation of more stringent environmental regulations and because of competitive reasons. According to a survey it was found that 65% of companies believe that returns management is an important strategic tool for their business (Rogers and Tibben-Lembke, 2001). Generally, returns can be classified into three major areas. These include manufacturing, distribution and market returns (de Brito, Dekker and Flapper, 2004). The first two areas are related to the process of manufacturing of the product and distribution such as returns from surplus of raw material and quality control as well as product recalls and B2B commercial returns. The last area concerns users of products and involve warranties, end of product use and end of life returns.
Dynamicstyle rotation or “style switching” is one of those themes that is often addressed in conferences and sell-side papers but is, to our knowledge, fairly rarely implemented by practitioners. This reflects the difficulty involved in forecasting when value, growth, momentum, or indeed, some other style, may do well or badly. The idea one would want to implement is to determine when you would want to tilt your portfolio towards or away from a particular style before the market moved, that is to anticipate when one style starts or stops outperforming the other. Attempts to
Resistance to fatigue and muscle stiffness can be a risk factor for injury. Alentorn-Geli et al. (2015) analysed the risk of anterior cruciate ligament injury in male football players. Their results were that the players with an injury at the time of the test had higher values in Tc, Tr, and Ts in the RF and in Dm in the BF compared to those players without injuries. These results must be taken into account when choosing athletes with a high anterior cruciate ligament injury risk and also for designing adequate prevention programmes for anterior cruciate ligament injuries in female rugby players. As an alternative use, sand can also be used as an effective rehabilitation surface, as it reduces force impact due to its ability to absorb impact, which is useful for adequate injury rehabilitation (Impellizzeri et al., 2008). However, the higher fatigue on the sand surface demonstrated in this study requires a higher control of training load. This control would allow the use of sand for sport training due to the benefits in the athlete’s performance, incorporating exercises on sand during their firm surface training (Mirzaei et al., 2013).
Figure 8 shows basically the sensitivity of the results due to changing some of the input parameters. It is rather clear that by changing some parameters in the realization of the borehole heat exchanger, the results change both in the borehole thermal resistance and in the ground thermal conductivity calculations made by using the infinite line source method. As can be seen clearly from Table 3, by changing the grout thermal conductivity (cases 1 and 2) and keeping the same all the other parameters, we obtain different results be- cause of the different borehole thermal resistances linked to the grout conductivity. Be- tween case 2 and case 4, we had only the temperature of the ground changed from a variable (with average of 14.3°C) to a constant one of 14.3°C, and what we experience is a very small difference in the result (less than 1% difference between the resistances and 3% between thermal conductivities), while in cases 3 and 6, in which the only difference lies in the underground temperature, the difference between the result is much higher (less than 3% difference between the resistances and 6% between thermal conductivities). Concerning the difference between cases 4 and 5, by changing only the reference temperature, nothing changes in the results (the borehole thermal resistance and ground thermal conductivity are the same for each borehole in the two cases).
higher-resolution subtractive process can achieve greater precision some printable polymers such as ABS, allow the surface finish to be smoothed and improved using 3D printer based on similar. Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts.
This situation represented both a unique opportu- nity to study landscape dynamics and a unique opportu- nity to build consensus about how the system works and how to manage it. The Atchafalaya landscape is chang- ing rapidly enough to provide time-series observations that can be used to test basic hypotheses about how coastal landscapes develop. In addition to short-term observations, there is a uniquely long and detailed history of field and remotely sensed data available on the study area (Bahr and others 1983, Costanza and others 1983). Solutions to the land loss problem in Louisiana all have far-reaching implications. They de- pend on which combination of solutions are under- taken and when and where they are undertaken. Out- side forces (such as rates of sea level rise) also influence the effectiveness of any proposed solution. In the past, suggested solutions have been evaluated independently of each other, in an ad hoc manner, and without adequate dialog and consensus among affected parties. In order to address this problem in a more compre- hensive way, a project was started in 1986 to apply the three-stage modeling approach described above. The first stage of scoping and consensus building involved mainly representatives of the Corps of Engineers, the US Fish and Wildlife service, local landowners and environmentalists, and several disciplines within the academic community. This stage involved a series of workshops aimed at developing a unit model, using STELLA, of the basic processes occurring at any point in the landscape, and at coming to agreement about how to model the entire landscape in the later stages. This stage took about a year.
In this wind turbine system under vector control of active and reactive power of DFIG connected to the grid the axis transformation is used that is based on reference frame theory. This transformation used on current, voltage vectors of stator and rotor from stationary reference frame into two phase rotating d-q reference frame. Stator side converter control is used to regulate the voltage across the DC link and maintain it’s constant, sometime also to compensate harmonics. Voltage vector scheme is a two stage controller scheme which is achieved by voltage oriented vector control scheme by aligning the d-q axis in the direction of stator voltage. Stator or Grid converter is typically a three phase, two level voltage source converter which uses the switching device as IGBT, the main purpose of stator side converter control is done to maintain constant the DC link voltage. This has been done by implementing grid voltage oriented control scheme. In the stator voltage orientation control, the grid voltage is measured the angle, and it is detected from phase lock loop for the voltage orientation and transformation of the axis.
This paper discussed the effect of Unified Power Flow Controller (UPFC) controllers for enhancement of power system voltage regulation and power flows in the transmission system. The model of UPFC are studied and validated in power system computer aided design & electromagnetic transient direct current (PSCAD/EMTDC) environment. The basic operations are explained, as well as the control strategies and circuit configurations of the controller. PI controller is used for control scheme. In this proposed work, the 4 bus test system is used to verify the proposed model. The steady-state analysis is done to show the capability of the controller in improving voltage regulation in the transmission system.