Low Cost GPS-Based System for Site-Specific Farming at Flat Terrains - Case Study

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): Low Cost GPS-Based System for Site-Specific Farming at Flat Terrains - Case Study. Manuscript ATOE 07 004. Vol. IX. July, 2007

A Frequency Multiplier Based on Time Recursive Processing

This paper describes a digital frequency multiplier for a pulse rate. The multiplier is based on the recursive processing of the input and output periods and their time differences. Special emphasis is devoted to the techniques which provide the development of multipliers based on this principle. The circuit is defined by two system parameters. One is the ratio of two clock frequencies and the other is a division factor of a binary counter. The realization of the circuit is described. The region of the system parameters for the stable circuit is presented. The different aspects of applications and limitations in realization of the circuit are considered. All mathematical analyses are made using a Z transform approach. It is shown that the circuit can be also used in tracking and prediction applications. Computer simulations are performed to prove the correctness of the math and the whole approach

Seismic assessment of a heavy-timber frame structure with ring-doweled moment-resisting connections

The performance of heavy-timber structures in earthquakes depends strongly on the inelastic behavior of the mechanical connections. Nevertheless, the nonlinear behavior of timber structures is only considered in the design phase indirectly through the use of an R-factor or a q-factor, which reduces the seismic elastic response spectrum. To improve the estimation of this, the seismic performance of a three-story building designed with ring-doweled moment resisting connections is analyzed here. Connections and members were designed to fulfill the seismic detailing requirements present in Eurocode 5 and Eurocode 8 for high ductility class structures. The performance of the structure is evaluated through a probabilistic approach, which accounts for uncertainties in mechanical properties of members and connections. Nonlinear static analyses and multi-record incremental dynamic analyses were performed to characterize the q-factor and develop fragility curves for different damage levels. The results indicate that the detailing requirements of Eurocode 5 and Eurocode 8 are sufficient to achieve the required performance, even though they also indicate that these requirements may be optimized to achieve more cost-effective connections and members. From the obtained fragility curves, it was verified that neglecting modeling uncertainties may lead to overestimation of the collapse capacity

Optimal placement and sizing of battery energy storage using the genetic algorithm

Voltage drop and rise at network peak and off-peak periods are one of the major power quality problems in low voltage distribution networks. Additionally, the ever increasing demand for electricity along with the other requirements are driving modern day power systems towards more distributed generation (DG). Integration of large scale DG can be limited by these voltage variations. Therefore, it is of high interest to investigate the voltage support strategies that are able to successfully mitigate these problems. One of the solutions is to use energy storage systems (ESS). On the one hand limited amount of energy storage might not have the desired impact. On the other hand it is not possible to install large amount of energy storage as this would increase the costs substantially. Therefore it is required to optimally place and size energy storage. The purpose of this thesis is to investigate the optimal placement and sizing of battery energy storage with the integration of renewable energy sources (RES) in a low voltage distribution network. An optimization model has been developed in order to identify the potential battery size and location combinations that increase the RES hosting capacity of the distribution network. The optimization tool used for this problem is the Genetic Algorithm (GA). Among the most important features of this algorithm stands its robustness and ability to provide good results in optimization processes. The functionality and the performance of the developed model is assessed using an IEEE benchmark network that has shown to be adequate for both the dynamic and steady-state analysis. The results of this work show that the voltage problems caused by the integration of RES can be mitigated by optimal placement and sizing of battery energy storage. They also show that besides the the voltage profile improvement reduction of losses can be achieved.Electrical Engineering, Mathematics and Computer ScienceElectrical Sustainable EnergyErasmus Mundus, European Wind Energy Master (EWEM

Experimental-numerical analyses of the seismic behaviour of cross-laminated wall systems

The paper discusses experimental and numerical seismic analyses of typical connections and wall systems used in cross-laminated (X-Lam) timber buildings. An extended experimental programme on typical X-Lam connections was performed at IVALSA Trees and Timber Institute. In addition, cyclic tests were also carried out on full-scale single and coupled X-Lam wall panels with different configurations and mechanical connectors subjected to lateral force. An advanced non-linear hysteretic spring to describe accurately the cyclic behaviour of connections was implemented in ABAQUS finite element software package as an external subroutine. The FE model with the springs calibrated on single connection tests was then used to reproduce numerically the behaviour of X-Lam wall panels, and the results were compared with the outcomes of experimental full-scale tests carried out at IVALSA. The developed model is suitable for evaluating dissipated energy and seismic vulnerability of X-Lam structures

Vibration Analyses of an Hybrid Concrete and Cross-laminated Timber Building Case Study

Nowadays, some innovative spatial structural typologies among others rely on timber-concrete hybrid solutions for designing modern buildings. However, the dynamic identification analysis may be more elaborate, and sometimes troublesome, due to the coupling effects of the different dynamic nature of cross-laminated timber and reinforced concrete members. In the current manuscript, the authors explore some preliminary results of the dynamic analysis of a hybrid timber concrete building case study. The operational modal analysis (OMA) based on output-only techniques has been employed, referring specifically to enhanced frequency-domain decomposition (EFDD) and the stochastic subspace identification (SSI) methods. The authors compared several ambient vibration OMA results with forced shaker-induced vibration responses highlighting the absence of nonlinearities during in-service operational conditions in two different moments