Palyno-anatomical characters and their systematic significance in the family Apiaceae from Chitral,eastern Hindu Kush,Pakistan

The present study was performed to provide a detailed explanation of leaf epidermal anatomy and pollen micromorphological features of selected species of family Apiaceae from Chitral, eastern Hindu Kush region as the basis of forthcoming studies. In the present article pollen morphology of eight species and foliar epidermal of seven species of family Apiaceae have been examined through microscopic techniques. In results two types of pollen prolate (five species) and perprolate (three species) with three colpi have been recorded. The exine ornamentation was found to be regulate, striate, and cerebroid. Largest pollen was found in Heracleum leucocarpum with the polar diameter of 43.25 μm and equatorial diameter of 21.6 μm. Smallest pollen was observed in Elaeosticta chitralica with the polar diameter of 18.4 μm. The P/E ratio varied from 1.59 to 2.16. Regarding to foliar epidermal anatomy, three types of epidermal cells including rectangular, irregular, and polygonal with variation in anticlinal wall pattern were determined. In the selected species three kinds of stomata comprising anisocytic, anomocytic, and paracytic type were reported in the current research. The size of epidermal cells ranged from 106 × 42.50 μm in Bupleurum falcatum subsp. cernuum and 77.25 × 26.35 μm in Prangos pabularia in adaxial surface. Largest stomatal complex was found in Prangos pabularia both in adaxial 33.55 × 20.05 μm and abaxial 50.25 × 39.40 μm. All the observed quantitative and qualitative features of the species were proved to be useful in the delimitation of species at generic and species level.     

Pollen morphology and its taxonomic potential in some selected taxa of Caesalpiniaceae observed under light microscopy and scanning electron microscopy

Pollen micromorphology is not only used to check the functional and structural evolution in plants but also to solve the taxonomic problem related to the classification of plants. Therefore, keeping in view the significance of pollen traits, selected taxa of the subfamily Caesalpiniaceae was collected from different geographical regions of Pakistan. The species were then analyzed under both light microscopy and scanning electron microscopy techniques to investigate the importance of micromorphological characters of pollen in the identification and classification of species. Great variation was recorded in equatorial shape, surface ornamentation, tectum, polar diameter, equatorial diameter, and exine thickness. However, little variation was observed in pollen type, polar shape, and fertility of pollen. The equatorial shape of five types was observed: prolate, prolate-spheroidal, spheroidal-subprolate, subspheroidal-prolate, and subspheroidal. Four types of surface ornamentation, psilate, granulate, clavate, and perforate, were recorded. Tectum of five types, intactate, reticulate regulate, medium reticulate, tactate, and striate, was observed. Sexine was thicker than nexine in all studied species. The largest polar diameter was observed in Caesalpinia pulcherrima 64.1 μm while the smallest in Parkinsonia aculeata 26.1 μm. The largest equatorial diameter was found in C. pulcherrima of 70.25 μm whereas the smallest in P. aculeata 27.57 μm. All the pollens analyzed were tricolporate. All studied species have a fertility ratio of more than 90%. A taxonomic key was developed to show the variation in pollen features and delimit species for the correct identification. In conclusion, the pollen traits were found useful to define species boundaries at various taxonomic ranks and will strengthen the taxonomy of this subfamily. Besides, this study also explored the palynological traits and their implication in the taxonomy of the subfamily Caesalpiniaceae.     

Evaluation of surrogate models for optimization of herringbone groove micromixer

Surrogate models have been applied to shape optimizations of a micromixer with the aim of assessing the performance of the models. The surrogate models considered include polynomial response surface approximation, Kriging, and radial basis neural network. In addition, a weighted average model based on global error measures is constructed. A mixing index at the exit of the micromixer is used as the objective function. The mixing index is calculated based on Navier-Stokes equations. Two cases of optimization, one with two design variables and the other with three design variables, have been tested. The design variables are selected among the ratio of the groove depth to channel height, the angle of groove, and the ratio of groove width to groove pitch. D-Optimal design generated sampling points are used for sampling. It is found that although the weighted average model does not predict the best optimal point, it does show consistent and reliable performance.     

Stabilization loop of a two axes gimbal system using self-tuning PID type fuzzy controller

The application of inertial stabilization system is to stabilize the sensor's line of sight toward a target by isolating the sensor from the disturbances induced by the operating environment. The aim of this paper is to present two axes gimbal system. The gimbals torque relationships are derived using Lagrange equation considering the base angular motion and dynamic mass unbalance. The stabilization loops are constructed with cross coupling unit utilizing proposed fuzzy PID type controller. The overall control system is simulated and validated using MATLAB. Then, the performance of proposed controller is evaluated comparing with conventional PI controller in terms of transient response analysis and quantitative study of error analysis. The simulation results obtained in different conditions prove the efficiency of the proposed fuzzy controller which offers a better response than the classical one, and improves further the transient and steady-state performance.     

ABSs系统模糊控制器优化设计

已经开发了的ABSs系统改善了突然制动和特别是滑动路面状况时车辆控制。这样的控制目标是在保持车辆合适稳定性及可操纵性和缩短车辆刹车距离情况下在要求的方向增大车轮的牵引力。本文提出了ABSs系统优化的模糊控制器。从保持其车轮滑动值为目标函数获得车轮最大的牵引力和车轮最大的减速度。采用遗传算法优化模糊系统的全部组件。采用误差数整体优化方法收敛接近最优点。仿真结果表明快速收敛和对不同路况的控制器的最好性能。     

PI/PID controller design based on IMC and percentage overshoot specification to controller setpoint change

In this work, the normalized Internal Model Control (IMC) filter time constant is designed to achieve a specified value of the maximum sensitivity for stable first and second order plus time delay process models, respectively. Since a particular value of the maximum sensitivity results in an almost constant percentage overshoot to controller setpoint change, an empirical relationship between the normalized IMC filter time constant and percentage overshoot is presented. The main advantage of the proposed method is that only a user-defined overshoot is required to design a PI/PID controller. Simulation examples are given to demonstrate the value of the proposed method.     

Investigation on the feasibility of eliminating harmonic excitation signal en-route to performing experimental modal analysis (EMA) under operational condition

This study focuses on introducing a criteria for conducting harmonic excitation signal elimination as well as investigating its effectiveness towards achieving complete isolation of harmonic disturbance in performing EMA under operational condition. By modulating the ratio between harmonic excitation and impact knocking frequencies, it was revealed that the harmonic signal was efficiently attenuated with sufficient number of averaging blocks. The results highlighted close agreement between simulation and experimental approaches with maximum deviation of 2 %, under specific design criteria. It was determined that a non-periodic triggering frequency significantly affect the elimination performance in terms of trend and amplitude reduction. This work underlines the importance of controlling the triggering frequency to yield the desired design criteria for achieving rapid and highly efficient elimination of harmonic excitation signal. The results have proven that the proposed technique can be further adapted to isolate the harmonic in conventional EMA conducted under operational condition.     

Aircore mechanism during draining based on influence of pressure difference and drain port diameter

An understanding of the mechanism of aircore phenomenon during draining is very important. In this study, numerical simulations were conducted for different pressurized and suction pressure water tanks, as well as for different drain port diameters, to explain and validate the proposed aircore mechanism. It was found that increasing the pressure at the top surface of the tank results in suppression of the aircore, whereas an increase in the suction pressure at the drain port outlet enhances the development of the aircore. For different drain port diameters, it was observed that the duration of the aircore during draining decreases with a decrease in the drain port diameter, and that the aircore is suppressed for a very small drain port diameter.