The touch trigger probe plays an important role in modern metrology because of its robust and compact design with crash protection, long life and excellent repeatability. Aside from coordinate measuring machines (CMM), touch trigger probes are used for workpiece location on a machine tool and for the accuracy assessment of the machine tools. As a result, the accuracy of the measurement is a matter of interest to the users. The touch trigger probe itself as well as the measuring surface, the machine tool, measuring environment etc. contribute to measurement inaccuracies. The paper presents the effect of surface irregularities, surface wetness due to cutting fluid and probing direction on probing accuracy on a machine tool.
The central theme of this work was to analyze high aspect ratio structure having structural nonlinearity in low subsonic flow and to model nonlinear stiffness by finite element-modal approach. Total stiffness of high aspect ratio wing can be decomposed to linear and nonlinear stiffnesses. Linear stiffness is modeled by its eigenvalues and eigenvectors, while nonlinear stiffness is calculated by the method of combined Finite Element-Modal approach. The nonlinear modal stiffness is calculated by defining nonlinear static load cases first. The nonlinear stiffness in the present work is modeled in two ways, i.e., based on bending modes only and based on bending and torsion modes both. Doublet lattice method (DLM) is used for dynamic analysis which accounts for the dependency of aerodynamic forces and moments on the frequency content of dynamic motion. Minimum state rational fraction approximation (RFA) of the aerodynamic influence coefficient (AIC) matrix is used to formulate full aeroelastic state-space time domain equation. Time domain dynamics analyses show that structure behavior becomes exponentially growing at speed above the flutter speed when linear stiffness is considered, however, Limit Cycle Oscillations (LCO) is observed when linear stiffness along with nonlinear stiffness, modeled by FE-Modal approach is considered. The amplitude of LCO increases with the increase in the speed. This method is based on cantilevered configuration. Nonlinear static tests are generated while wing root chord is fixed in all degrees of freedom and it needs modification if one requires considering full aircraft. It uses dedicated commercial finite element package in conjunction with commercial aeroelastic package making the method very attractive for quick nonlinear aeroelastic analysis. It is the extension of M.Y. Harmin and J.E. Cooper method in which they used the same equations of motion and modeled geometrical nonlinearity in bending modes only. In the current work, geometrical nonlinearities in bending and in torsion modes have been considered.
The growth in the system load accompanied by an increase of power loss in the distribution system. Distributed generation (DG) is an important identity in the electric power sector that substantially overcomes power loss and voltage drop problems when it is coordinated with a location and size properly. In this study, the DG integration into the network is optimally distributed by considering the load conditions in different load models used to surmount the impact of load growth. There are five load models tested namely constant, residential, industrial, commercial and mixed loads. The growth of the electrical load is modeled for the base year up to the fifth year as a short-term plan. Minimization of system power loss is taken as the main objective function considering voltage limits. Determination of the location and size of DG is optimally done by using the breeder genetic algorithm (BGA). The proposed studies were applied to the IEEE 30 radial distribution system with single and multiple placement DG scenarios. The results indicated that installing an optimal location and size DG could have a strong potential to reduce power loss and to secure future energy demand of load models. Also, commercial load requires the largest DG active injection power to maintain the voltage value within tolerable limits up to five years.
A thermoacoustic heat engine (TAHE) converts heat into acoustic power with no moving parts. It exhibits several advantages over traditional engines, such as simple design, stable functionality, and environment-friendly working gas. In order to further improve the performance of TAHE, stack parameters need to be optimized. Stack’s position, length and plate spacing are the three main parameters that have been investigated in this study. Stack’s position dictates both the efficiency and the maximum produced acoustic power of the heat engine. Positioning the stack closer to the pressure anti-node might ensure high efficiency on the expense of the maximum produced acoustic power. It is noticed that the TAHE efficiency can further be improved by spacing the plates of the stack at a value of 2.4 of the thermal penetration depth, δk. Changes in the stack length will not affect the efficiency much as long as the temperature gradient across the stack, as a ratio of the critical temperature gradient Γ; is more than 1. Upon interpreting the effect of these variations, attempts are made towards reaching the engine’s most powerful operating point.
The investigation was conducted in 2004 and 2005 to test 28 sesame genotypes for resistance and susceptablity to Rhizoctonia solani under artificial infection conditions at the Plant Breeding Experimental Farm of the Faculty of Agriculture, Suez Canal University, Ismailia, Egypt. All screened sesame genotypes showed varied significant degrees of infestation with the root rot pathogen. It is worth to mention that some of sesame genotypes kept their resistance characterestic classes as moderately resistant (MR) or resistant (R) during the two successive seasons. Such genotypes might be useful for breeding programs due to stability of their resistant character as well as their seed yield. Phenotypic coefficients of variation (P.C.V.) and genotypic coefficients of variation (G.C.V.) were of high value regarding resistance characters during both seasons and comparable to seed yield character. The heritability estimates indicate that selection is a suitable way for picking up sesame genotypes that have high chance for resistance character to root rot disease (R. solani) with high seed yield potential. The genetic advance and heritability estimates in all cases supported the selection of some sesame genotypes to be used in next breeding programs for root rot resistance, they also showed a high seed yield potential.
In this work, response surface optimization strategy was employed to enhance the biodegradation process of fresh palm oil mill effluent (POME) by Aspergillus niger and Trichoderma virens. A central composite design (CCD) combined with response surface methodology (RSM) were employed to study the effects of three independent variables: inoculum size (%), agitation rate (rpm) and temperature (°C) on the biodegradation processes and production of biosolids enriched with fungal biomass protein. The results achieved using A. niger were compared to those obtained using T. virens. The optimal conditions for the biodegradation processes in terms of total suspended solids (TSS), turbidity, chemical oxygen demand (COD), specific resistance to filtration (SRF) and production of biosolids enriched with fungal biomass protein in fresh POME treated with A. niger and T. virens have been predicted by multiple response optimization and verified experimentally at 19% (v/v) inoculum size, 100 rpm, 30.2°C and 5% (v/v) inoculum size, 100 rpm, 33.3°C respectively. As disclosed by ANOVA and response surface plots, the effects of inoculum size and agitation rate on fresh POME treatment process by both fungal strains were significant.
Beamforming is an advanced signal processing technique used in sensor arrays for directional signal transmission
or reception. The paper deals with a system based on an ultrasound transmitter and an array of
receivers, to determine the distance to an obstacle by measuring the time of flight and – using the phase
beamforming technique to process the output signals of receivers for finding the direction from which the
reflected signal is received – locates the obstacle. The embedded beam-former interacts with a PID-based
line follower robot to improve performance of the line follower navigation algorithm by detecting and
avoiding obstacles. The PID (proportional-integral-derivative) algorithm is also typically used to control
industrial processes. It calculates the difference between a measured value and a desired set of points, then
attempts to minimize the error by adjusting the output. The overall navigation system combines a PID-based
trajectory follower with a spatial-temporal filter (beamformer) that uses the output of an array of sensors to
extract signals received from an obstacle in a particular direction in order to guide an autonomous vehicle
or a robot along a safe path.
Early blight disease caused by Alternaria sp. is one of the most devastating diseases of
Solanaceous crops widely distributed in Sudan. The aim of this study was to determine the
genetic variation among different Alternaria isolates recovered from different Solanaceae
crops showing typical symptoms of early blight disease. Infected leaves of tomato, potato,
eggplant and pepper were collected from different geographical zones in Sudan. The recovered
fungal isolates were identified to the genus level based on cultural and morphological
characteristics. Five representative isolates were sent to the CABI Bioscience, U.K. for confirmation.
The genetic relationship among the isolates was determined using the amplified
fragments length polymorphism (AFLP) technique and the generated data were used to
create similarity matrices using the PAST 3.01 software package. Dendrograms were constructed
based on Jaccard’s similarity coefficients. A total of 70 fungal isolates was recovered
from the tested plants and all of them showed morphological characteristics typical
of Alternaria spp. The conidia appeared in multiple-branched chains with spore sizes in
the range of 2.38−13.09 μm × 12.30−43.63 μm. Therefore, the isolates were identified as
Alternaria alternata (Fr.) Keissl. The identification was then confirmed by CABI.AFLPbased
dendrogram which revealed five clusters with a significant cophenetic correlation
coefficient (r = 0.834) between the dendrogram and the original similarity matrix irrespective
of their geographical origins. Eighteen (75%) of the Alternaria isolated from tomato
leaves were clustered together in cluster I and five isolates formed two separate clusters,
viz. cluster IV (T-Kh5 and T-H1) and cluster V (T-H4 and T-Med2). The remaining isolate,
T-Am5, grouped with one of the potato isolates in cluster III. The other isolates which were
recovered from potato, pepper and eggplants were all separated from the tomato isolates
in the largest cluster.