The ultimate goal of this work is to find a region where the response surface of a function that is not well characterized in terms of optimality resembles one that is well-characterized in such terms to find, at least, a local optimum. The region in the functions’ input space where this resemblance occurs, we call a Window of Maximal Similarity (WMS) and is identified by formulating and solving an optimization problem. The method is one of minimization of squared errors and can be used to explore experimental, or simulated data. A series of examples, that include several typical global optimization test functions in literature, are presented in order to demonstrate the method’s feasibility and capability for generating a two-dimensional WMS. This tool is a viable element that will serve for the future development of Optimization by Similarity.
In this paper we present design of RTL-SDR based low cost receiver for meteorological balloon telemetry. In developed receiver all the demodulation processes are performed in software developed in LabVIEW. Design and fabrication of Quarter Wave Monopole Antenna and Quadrifilar Helix Antenna (QHA) is also presented for use with the receiver. Antennas are selected such that the combined beam pattern provides optimum coverage in both low and high elevation angles. This system is designed to operate in meteorological-aids frequency band of 400-406 MHz. Paper presents bit error rate performance of developed receiver. Performances of the RTL-SDR receiver using both the antennas are assessed by processing the signals received from the radiosonde flights at Gadanki (13.46°N, 79.17°E). Finally it is shown that RTL-SDR based receiver can receive signals up to the range of about 75-80 Km.
The paper presents a novel technique to detect the solvents in water like sugar, salt, and its combination using a wideband CPW fed microstrip antenna with periodic EBG ground structure. The antenna is designed and fabricated to operates at the bandwidth of 3 GHz with a stable gain of 9 dBi maintaining VSWR<2. The uniquely designed antenna works as a sensor in its near field to sense the solvents in water in terms of resonant frequency and reflection method in wider bandwidth. The technique also detects the changes in the temperature of the soft drinks as a function of reflection characteristics. This technique will be useful for finding the percentage of solvents in soft drinks before consumption. The sensing technique is without physical contact with the solution and chemical process. Therefore it is a healthy way to find the ingredients in solutions like soft drinks. The technique will be useful to the food regulation boards to limit the contents of beverages and cold drinks.
Reduction in the torsional vibration of heavy rotors like turbo-generator rotor is important for the safe and efficient functioning of the power plant. In this paper theoretical study is performed to control the torsional vibration in the turbo-generator rotor using piezoelectric material as sensor and actuator. Polyvinylidene fluoride (PVDF) layer is used as sensor and actuator. Proportional and velocity feedback is used as control law. The variation in the electromagnetic torque of synchronous generator during various electrical faults is evaluated using dq0 model. Finite element method is used to model the rotor elements. The coupled equations are solved in MATLAB using Newmark-beta integration method. The coupling elements of turbine and generator are most susceptible to the shear failure so torsional vibration of coupled rotor on coupling elements are compare for controlled and uncontrolled scenario. Simulation results show that for actively controlled rotor significant reduction in the amplitude of torsional vibrations is observed.
Rationale and objectives: Changes in, and predictors of, quality of life (QoL) among unstable angina patients are informative for both clinical and public health practice. However, there is little research on this topic, especially in healthcare settings with limited resources. This study aims to detect changes in QoL and its associated factors among patients with unstable angina after percutaneous coronary intervention. Methods: A quasi-experimental design was conducted with two repeated rounds of measurements, one month and three months after intervention, using the generic SF-36 questionnaire, in 120 patients from Vietnam National Heart Institute. A linear mixed-effects model was used to assess changes in patient QoL over time while adjusting for other covariates. Results: Only 2 out of 8 QoL subscales (social functioning and emotional well-being) declined after one month, but these tended to rise again after three months, while scores of all other QoL subscales increased. Adjusting for covariates, QoL increased slightly after one month of intervention (β=0.65, 95%CI=-0.86-2.16) but improved by almost 6 QoL points after 3 months (β=5.99, 95%CI=4.48-7.50). Four confounders significantly associated with a decline in QoL were older age, being retired, living in rural areas, and having abnormal troponin level. Conclusion: QoL of the patients with unstable angina improves significantly three months after intervention, rather than after one month. To increase QoL, it is important to address risk factors and to improve the quality of healthcare delivery.
Cerasus serrulata (Rosaceae) is an important flowering cherry resource. It is almost the most widely distributed species in the genus, mainly included in the subtropical and temperate China, which enables the geographic evolutionary pattern to be a representative. Besides, the morphological traits are greatly varied especially in ornamental characters. All of these makes Cerrasus serrulata a valuable research object. Thus, phylogeographic analysis was conducted to apprehend the spatial pattern and evolutionary history, which can also add insights into the phylogeography of the genus Cerasus and plants in subtropical and temperate China, as well as to deeper understand the genetic diversity and structure of the germplasm to make better and more effective utilization. A total of 327 individuals of 18 populations were collected. Three cpDNA fragments (matK, trnD-E, trnS-G) and the nuclear internal transcribed spacer (ITS) were utilized. The result showed a high genetic diversity both in species level and population level of Cerrasus serrulata. The high genetic differentiation among populations and the existence of phylogeographic structure in whole were detected. In addition, no bottleneck was identified. The the distribution pattern and center were formed before the LGM. Two geographical lineages were inferred. One was confined to Qingling Mountain and Taihang Mt. The other was from the Wuling Mt to Lu-Huang Mt, and then went northeast to the coast of Asia. Besides, taxonomic treatments of the Cerasus serrulata complex were reconsidered.
A new transport model is proposed for paraffin wax deposition onto a cold finger from flowing wax-containing oils. The model solves transient energy and mass balances simultaneously for a reversible first-order kinetic rate for precipitation of pseudo-single-component wax, and the effects of yield stress using a critical solid wax concentration to withstand flow-induced stress at the deposit-fluid interface, Cpi. The model can predict the time evolution of the deposit thickness, and the spatial and temporal evolution of temperature and wax concentration and was validated using experiments involving a cylindrical cold finger. We found that for oils with Cpi close to zero, the deposit thickness growth is dominated by heat transfer. However, mass transfer cannot be neglected as diffusion of wax into the deposit continues to take place even after the deposit has stopped growing. For oils with non-zero Cpi, the deposit growth is slow and accompanied by occasional sloughing.
Groundwater dependent ecosystems (GDEs) must have access to groundwater to maintain their ecological structure and function. The rapid expansion of humans has increased demands on groundwater for consumption, industry and agriculture, these demands alter groundwater regimes of natural GDEs, resulting in the degradation of ecosystem health. In order to improve the conceptual understanding of the role of groundwater in such ecosystems, this study examined key aspects of GDEs (hydrogeology, hydrogeochemistry and biodiversity) in the Langxi river watershed, North China. Results indicate that the karst in Langxi river watershed is well developed. The water chemistry types in the watershed were mostly HCO3-Ca type with different clustering characteristics, which indicate different degrees of interaction between surface water and groundwater, and that the recharge processes and flux of GDEs are different. Land use type and humidity maps were obtained by remote sensing interpretation, and combined with the groundwater isolines, it can be seen that in the dry season, when the groundwater level higher than the maximum depth of vegetation root system, and areas with high humidity, were the GDEs distribution areas. Water quality of the Longchi and Zhangxia Group aquifer is good and the content of Sr is high, suggesting that it can be used as a partial strontium type natural mineral water. It was also found that there are several types of stygofauna in the GDEs of the Langxi river watershed, indicating that the water quality of the sampling points has not been contaminated.
Acquired drug resistance syndrom (ADR) is one of the most important features associated with tumor treatment and it is therefore a~topic of intensive studies. We present two simple mathematical models reflecting different mechanisms of ADR with some Darwinian effects included. These effects allow resistant cells to become sensitive again. Basing on this mathematical approach we conclude that for constant continuous treatment, if no Darwinian effects are present then once resistant cells appear, sensitive cells are eliminated after a long time, independently of the mechanism of acquiring the resistance. However, with Darwinian effects the situation is a little better as the sensitive cells are not completely eliminated but they are still outcompeted by the resistant ones. Moreover, if the therapy is stopped resistant cells become dominated by sensitive cells and the situation changes completely in comparison to the case without Darwinian effects. We discuss these mechanisms on the example of gliomas.
Wind energy is one of the clean, sustainable types of energy that can deal with the current worldwide non-renewable energy source emergency. Even though it adds to 2.5% of the worldwide power request, with depletion of petroleum derivative sources, extraction of wind energy must reach to a more prominent degree to meet the energy emergency and issue of contamination. Now, to improve the aerodynamic response of a wind turbine, the blade pitch control is an effective method, usually applied to large-scale wind turbines. The present work incorporates an investigation of the impact of varied pitch angles on the performance parameters of a horizontal axis wind turbine. CFD code Fluent has been used to perform the simulations. A total of eight pitch angles are considered in this investigation. In addition to it, a numerical investigation of S809 airfoil has been performed and validated by a series of benchmark data. The SST k-w turbulence model has been utilized. The steady-state simulation is performed around a HAWT blade using multiple reference frame. It is seen that torque increases with an increase in wind velocity and decreases with an increase in pitch angle. The optimum pitch angle is obtained for maximum power generation.
The synthetic rubber industry is of great importance and it is present in the daily life of world society. BR (butadiene rubber or polybutadiene) is one of the most used polymers in this field, mainly in tire production. Therefore, the control of operational conditions and final properties of the polymer formed are important points to be studied as they are a challenge for the industry. Thus, the present work focus in simulate the batch polymerization of polybutadiene using the Aspen Plus software, where 1,3-butadiene, titanium tetrachloride, triethylaluminium and hexane were used as monomer, catalyst, co-catalyst and solvent, respectively. Four cases were simulated changing the number of catalyst sites in order to predict and compare the final properties of polybutadiene resins including the average molecular weights, the molecular weight distribution and the evolution of operation conditions that are used at plant to monitor the course of the reaction like the reaction temperature and pressure.
In this manuscript, a two-port semi-circular patch antenna with Koch curve fractals is presented as a suitable candidate for portable UWB communication systems. The proposed fractal array is engraved on a 1.57 mm thick FR-4 substrate with an overall array size of 30.5 × 47 × 1.64 mm3. The upper substrate layer consists of two microstrip-line fed semi-circular patches combined with two Koch curve fractals (optimized up to 2nd order of iteration) separated by a distance of λ/2. To mitigate the effect of mutual coupling between the radiating elements, the lower substrate layer consists of a reduced ground plane with a funnel-shaped decoupling structure. To achieve a high degree of isolation (S21/S12 ≤ -16.8 dB) between the ports of the proposed array, two rectangular and L-shaped slots (mirror images of each other) are etched from the upper surface of the reduced ground. The design and simulation of the proposed antenna array is implemented in CST MWS’18. The optimized fractal array covers the simulated frequency band from 4.395-10.184 GHz with a fractional bandwidth of 79.4 % (at a center frequency of 5.789 GHz) and provides a peak radiation efficiency of 88.8% (at 6.2 GHz frequency). The antenna diversity performance is analyzed in terms of envelope correlation coefficient (ECC ≤ 0.0021), diversity gain (DG ≥ 9.989), mean effective gain (MEG ≥ -3.7 dB), channel capacity loss (CCL ≤ 0.4 bits/s/Hz) and total active reflection coefficient (TARC ≤ -10 dB). The experimentally measured S-parameter results show a good match with the simulated ones.
Tunnels had been undergone accidental and intentional blast in the past. An analysis of a rock tunnel when subjected to internal blast loading has been presented in this paper. A three-dimensional finite element model of a huge rock mass comprising the tunnel has been developed in Abaqus/CAE. Diameter of the tunnel has been kept constant to a two-lane transportation tunnel. However, liner thickness of the concrete, overburden pressure on the tunnel has been varied to observe the response in different possible conditions. To incorporate the elastoplastic response of rock mass, Mohr-Coulomb constitutive material model has been considered. For modelling of trinitrotoluene (TNT), Jones-Wilkins-Lee material model has been adopted. Concrete Damage Plasticity material model has been adopted for tunnel lining. For the blast loading, Coupled-Eulerian-Lagrangian (CEL) model has been considered. Results highlight the importance of tunnel lining thickness and overburden depth while designing the tunnel in rocks. Under any amount of explosive, deep tunnels have been found to be safer than shallow tunnel.
The main goal of this study is to determine the aerodynamic performance and to characterize unsteady flows in a high-speed high-reaction pre-whirl axial flow fan. The pressure waves’ main diametrical modes where two blades interact with two vanes and their sequences are predicted. There are mainly two mechanisms of IGV-rotor interactions identified; the first is attributed to the potential effect whereas the second is due to the wake-blade interaction and the advection of wake mixing into the blades’ passages. Both effects are dependent on the circumferential positions of blades and the axial inter-distance between IGV and rotor. The time mode analyses of pressure fluctuations recorded from different monitor points are determined and the frequencies of prevailing modes and those related to the vortical flow structure through the components are also identified. The understanding of vanes and blade rows interactions at various axial inter-distances is an important step in determining the beneficial and detrimental effects on the design of high performance axial fan stage.
Enzyme immobilization enhances the catalytic activity and stability of the enzyme, and also improves reusability. Metal organic frameworks (MOFs), which possess diversified structures and porosity, have been used as excellent carriers for enzyme immobilization. Pseudomonas fluorescens lipase (PFL) has been successfully immobilized onto MOFs by covalent cross-linking to obtain a series of immobilized lipase (PFL@MOFs). PFL@MOFs are used for catalytic enantioselective hydrolysis of 2-(4-hydroxyphenyl) propionic acid ethyl ester enantiomers (2-HPPAEE) in aqueous medium and transesterification of 4-methoxymandelic acid enantiomers (4-MMA) in organic medium. The experimental results indicated that PFL@Uio-66(Zr) exhibits excellent enzymatic catalysis performances and high enantioselectives. In addition, to increase catalytic activity and reusability, PFL is modified by the polyethylene glycol (PEG) to prepare PEG-modified lipase (PFL-PEG), then PFL-PEG is immobilized onto Uio-66(Zr) to prepare PFL-PEG@Uio-66(Zr), demonstrating better reusability and catalytic activity compared with PFL@Uio-66(Zr).
A study is considered to a steady, two-dimensional boundary layer flow of an incompressible MHD fluid for the Blasius and Sakiadis flows about a flat plate in the presence of thermo-diffusion (Dufour) and thermal-diffusion (Soret) effects for variable parameters. The governing partial differential equations are transformed into a system of nonlinear ordinary differential equations using similarity variables. The transformed systems are solved numerically by Runge-Kutta Gills method with shooting techniques. The variations of the flow velocity, temperature and concentration as well as the characteristics of heat and mass transfer are presented graphically with tabulated results. The numerical computations show that thermal boundary layer thickness is found to be increased with increasing values of Eckert number (Ec), Prandtl number (Pr) and local Grashof number (Gr_x) for both Blasius and Sakiadis flow. The Blasius flow elevates the thickness of the thermal boundary layer compared with the Sakiadis flow. The local magnetic field has shown that flow is retarded in the boundary layer but enhances temperature and concentration distributions.
We present a novel radar signal processing technique to identify the presence or absence of a living body in a vehicle using a mm-wave frequency-modulated continuous-wave radar. Unlike traditional detection methods which are mostly based on constant false alarm rate (CFAR), our proposed method extracts and monitors the consistent Doppler effect of received signals from the radar antenna resulting from the consistent breathing of living bodies over time. The proposed method works in all types of cars without the need for threshold definition for tracking as well as no need for training. Hence, the algorithm is more robust, accurate and fast. We assess our proposed signal processing with two phantoms mimicking the breathing of children and with adults in the vehicle in various conditions. The system has been proven to be robust in extensive studies over the course of multiple months.
This work focused on the chemical synthesis and characterization of palm kernel oil (PKO) for bio-lubricant production using transesterification of palm kernel methyl ester (PKME) with trimethylolpropane (TMP) and epoxidation-esterification methods. The PKO was extracted using solvent extraction method. The physicochemical characteristics of the PKO and produced bio-lubricant samples were determined using standard methods. Fourier Transform Infrared (FTIR) spectrometry and Gas Chromatographic analyses, were respectively, used to determine the predominant functional groups and fatty acids of PKO and the produced bio-lubricant samples. At 55 °C, 150 min and 0.5 mm particle size, kernel oil yield was 49.82 % (by weight). The viscosities at 40 °C, 100 °C, viscosity index, pour and flash points of the bio-lubricants produced by transesterification of TMP (PKBLT) and epoxidation-esterification (PKBLE) methods, were [42.53 cSt, 10.65 cSt, 139, - 11 °C, 235 °C] and [44.69 cSt, 11.42 cSt, 132, - 12 °C, 240 °C], respectively. Time, mole ratio and temperature effects were the main factors that significantly influenced the transesterification and epoxidation processes. The obtained physicochemical properties of PKBLE and PKBLT samples showed conformity with ISO VG 32 standard, hence, their possible application as bio-lubricant basestock.