Design of MMIC oscillators using GaAs 0.2 μm PHEMT technology

We propose a feedback type oscillator and two negative resistance oscillators.These microwave oscillators have been designed in the S band frequency.A relatively symmetric resonator is used in the feedback type oscillator.The first negative resistance oscillator uses a simple lumped element resonator which is substituted by a microstrip resonator in the second oscillator to improve results.The negative resistance oscillator produces 4.207 dBm and 7.124 dBm output power with the lumped element resonator and microstrip resonator respectively,and the feedback type oscillator produces ?10.707 dBm output power.The feedback type oscillator operates at 3 GHz with phase noise levels at-83.30 dBc/Hz and-103.3 dBc/Hz at 100 kHz and 1 MHz offset frequencies respectively.The phase noise levels of the negative resistance oscillator with the lumped element resonator are-94.64 dBc/Hz and-116 dBc/Hz at 100 kHz and 1 MHz offset frequencies respectively,at an oscillation frequency of 3.053 GHz.With the microstrip resonator the phase noise levels are-99.49 dBc/Hz and-119.641 dBc/Hz at 100 kHz and 1 MHz offset frequencies respectively,at an oscillation frequency of 3.072 GHz.The results showed that both the output power and the phase noise of the negative resistance oscillators were better than those of the feedback type oscillator.     

Effects of post-packaging pasteurization process on microbial,chemical, and sensory qualities of ready-to-eat cured vacuum-packed Turkey breast

Ready-to-eat (RTE) cured vacuum-packed turkey breast was pasteurized (80°C, 5.5 min) and stored at 8°C (like supermarkets refrigerator temperature). After 42 days (current shelf life of this product), in control group (RTE cured vacuum-packed turkey breast), the number of mesophilic, anaerobic, lactic acid bacteria, mold and yeast, coliform, and psychrotrophic increased 5.82, 6.85, 5.85, 4.75, 1.49, and 5.57 log CFU/g, respectively. However, in the pasteurized samples, the number of mesophilic, anaerobic, and lactic acid bacteria increased 1.86, 2.12, and 2.28 log CFU/g, respectively, and mold and yeast, coliform, and psychrotrophic bacteria were under the detection limit. The effects of post-packaging pasteurization on the reduction of total mesophilic, anaerobic and lactic acid bacteria counts on Day 42 of storage was 7.04 ± 0.33, 4.73 ± 0.11, and 5.58 ± 0.11 log CFU/g, respectively. Sensory quality of treated samples was significantly better than the control's (p < .05). Post-packaging pasteurization (PPP) significantly inhibited the reduction in the pH and the increase in TVB-N, TBARS, titratable acidity, and drip loss (p < .05). This study shows the effectiveness of PPP on microbial, chemical, and sensory quality of cured vacuum-packed turkey breast during cold storage.     

Numerical modeling of natural convection in an open cavity with two vertical thin heat sources subjected to a nanofluid

This paper presents a numerical study of natural convection cooling of two heat sources vertically attached to horizontal walls of a cavity. The right opening boundary is subjected to the copper–water nanofluid at constant low temperature and pressure, while the other boundaries are assumed to be adiabatic. The governing equations have been solved using the finite volume approach, using SIMPLE algorithm on the collocated arrangement. The study has been carried out for the Rayleigh number in the range 10⁴ ≤ Ra ≤ 10⁷, and for solid volume fraction 0 ≤ φ ≤ 0.05. In order to investigate the effect of heat source location, three different placement configurations of heat sources are considered. The effects of both Rayleigh numbers and heat source locations on the streamlines, isotherms, Nusselt number are investigated. The results indicate that the flow field and temperature distributions inside the cavity are strongly dependent on the Rayleigh numbers and the position of the heat sources. The results also indicate that the Nusselt number is an increasing function of the Rayleigh number, the distance between two heat sources, and distance from the wall. In addition it is observed that the average Nusselt number increases linearly with the increase in the solid volume fraction of nanoparticles.     

Exploring the Potential of Drug Response Assays for Precision Medicine in Ovarian Cancer

One of the major challenges in the treatment of cancer are differential responses of patients to existing standard of care anti-cancer drugs. These differential responses may, in part, be due to a diverse range of genomic, epigenomic, proteomic, and metabolic alterations among individuals suffering from the same type of cancer. Precision medicine is an emerging approach in cancer therapeutics that takes into account specific molecular alterations, environmental factors as well as lifestyle of individual patients. This approach allows clinicians and researchers to select or predict treatments that would most likely benefit the patient based on their individual tumor characteristics. One class of precision medicine tools are predictive, in vitro drug-response assays designed to test the sensitivity of patient tumor cells to existing or novel therapies. These assays have the potential to rapidly identify the most effective treatments for cancer patients and thus hold great promise in the field of precision medicine. In this review, we have highlighted several drug-response assays developed in ovarian cancer and discussed the current challenges and future prospects of these assays in the clinical management of this disease.     

Synthesis of zeolite/magnetite nanocomposite and a fast experimental determination of its specific surface area

In the present work, the clinoptilolite was magnetized by magnetite nano-powder synthesized by chemical co-precipitation route. The clinoptilolite/magnetite nanocomposites were prepared with different weight ratios of 7 : 1, 5 : 1, 3 : 1 and 1 : 1 using FeCl₃ · 6H₂O and FeCl₂ · 4H₂O in an aqueous phase under the ambient condition. The nanocomposites were characterized by the X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and the vibrating sample magnetometer techniques. The results of characterization suggest that the main magnetic phase present in the nanocomposite is magnetite nanoparticle with an average diameter of 18–23 nm and the saturation magnetization of 74.29 emu g^–1. The specific surface area was calculated by a BET single-point method as a rapid and accurate way which can lie almost anywhere on the isotherm. The values of the specific surface area obtained by the BET single-point method were in a good agreement with the BET multiple-point method. It was found that the BET single-point method is faster and simpler than the BET multiple-point method for routine applications. Also, increasing Fe₃O₄ content caused an increase in the specific surface area of the nanocomposites.     

Middleman covert channel establishment based on MORE routing protocol using network coding in ad hoc networks

Covert channels have been recently the subject of the study in both creation and countermeasure aspects. There are many different ways to embed the covert data in network standards and protocols, especially in wireless networks. MORE (MAC‐independent opportunistic routing) is an opportunistic routing protocol which uses networks coding to enhance routing performance by reducing the repetitions. This protocol can be a suitable medium for covert channel establishment. A middleman covert channel establishment method is proposed in this paper over MORE routing protocol and with the use of network coding. Hidden data are transferred through packet's payload bytes. Covert sender manipulates coding mechanism by calculating packets' coefficients instead of random selection. The proposed covert channel provides the average throughput of 218 and 231 bps, using two different data length approaches which is relatively a good comparing to the previous network layer covert channels. The proposed covert channel is also a covert storage channel and cannot be removed or restricted. Effect of different network characteristics on the proposed method's capacity and security is investigated by a simulation study, and the results are discussed.     

A numerical study of the Navier–Stokes-αβ model

We present a numerical study of the NS-αβ model, which is a recently proposed multiscale variation of the NS-α model that attempts to recapture scales lost through over-regularization by separately modeling dissipation-range scales. We develop a similarity theory for the new model which shows that it is better equipped than the NS-α model to capture smaller-scale behavior. Next, we propose and study an unconditionally stable, optimally accurate, and efficient finite-element implementation for the NS-αβ model; rigorous proofs for stability and convergence are provided. Finally, we present results from two numerical experiments that demonstrate the advantages of the NS-αβ model over the NS-α model.     

Reliability modelling with redundancy—A case study of power generation engines in a wastewater treatment plant

Power generators are critical assets in wastewater treatment plants (WWTPs) in Australia and many countries. Better managing the lifetime, minimising failures, improving reliability and availability, and reducing operating and maintenance costs of the power generation assets are still challenging topics for water utilities. This case study aims to develop power generation system reliability and availability modelling considering redundancy to minimise operation and maintenance costs. The two-parameter Weibull model was used to assess system reliability and availability to power generation engines in WWTPs. The Kaplan-Meier method (a time-driven estimation technique) and the log beta-Weibull model (which is suitable for modelling censored and uncensored data) were used to analyse and validate the modelling results. Shape and scale parameters of the Weibull models were estimated by maximising the log-likelihood function using non-linear optimisation. Hazard and reliability functions were calculated using the Weibull model. Results using two-parameter Weibull, Kaplan-Meier, and log beta-Weibull models display low reliability and high hazard rate over time, which was associated with spark plug failure due to a suboptimal start and stop operation strategy.     

Retraction Note: Analytical investigations and fuzzy logic-based modeling of the impact resistance of aluminum-epoxy laminated composites

Science China Technological Sciences - This article has been retracted. Please see the retraction notice for more detail: https://doi.org/10.1007/s11431-021-1775-1     

A sensitivity study of the Navier–Stokes-α model

We present a sensitivity study of the Navier Stokes-$\alpha$ model with respect to perturbations of the differential filter length $\alpha$. The parameter-sensitivity is evaluated using the sensitivity equations method. Once formulated, the sensitivity equations are discretized and computed alongside the NS$\alpha$ model using the same finite elements in space, and Crank–Nicolson in time. We provide a complete stability analysis of the scheme, along with the results of several benchmark problems in both 2D and 3D. We further demonstrate a practical technique to utilize sensitivity calculations to determine the reliability of the NS$\alpha$ model in problem-specific settings. Lastly, we investigate the sensitivity and reliability of important functionals of the velocity and pressure solutions.