Minimum Gain Research Articles

Optimization of osmotic dehydration in dragon fruit (Hylocereus Polyrhizus) slices using response surface methodology

Dragon fruit (Hylocereus polyrhizus) is emerging as a super crop because of its several health and therapeutic benefits and ease of cultivation even in degraded land. Using response surface approach, the process parameters for osmotic dehydration of dragon fruit slices included process temperature, syrup concentration and process time. Slices of size 20 x 20 x 5 mm were dipped into sugar syrup with a syrup to dragon fruit slice ratio of 4:1 (w/w). After osmotic dehydration, the initial moisture content of dragon fruit samples was reduced to 27.5-68.49% (wb), demonstrating water loss, solid gain, and mass reduction in the range of 18.01-65.9%, 6.3-17.9% and 9.31-50.6%, respectively. After statistical analysis of the data on water loss, solid gain, and weight reduction, it was shown that regression equations of second order provided the greatest match for all the experimental data. With a syrup to fruit ratio of 4:1 and a syrup concentration of 65.3° Brix at a syrup temperature of 56.5°C, a maximum water loss of 58.2% and a minimum solid gain of 7.7% were expected to occur in 240 minutes of osmotic dehydration.

Experimental evaluation on OSNR and DMG performance of cascade FM-EDFA systems by equivalent input spectrum method

An all-fiber few-mode erbium-doped fiber amplifier (FM-EDFA) is constructed by the integration of few-mode isolator wavelength division multiplexers (FM-IWDMs), which act as the multiplexing or demultiplexing function between signal and pump light. The gain performance of the FM-EDFAs under forward, bidirectional and backward pumping cases is investigated by experiment. For LP01, LP11e and LP11o-mode signals, the minimum differential mode gain (DMG) of 0.14 dB can be achieved by forward LP11e and LP11o-mode pumping. We propose the equivalent input spectrum method to experimentally simulate the cascade FM-EDFA systems. For the three-mode amplification, the optical signal-to-noise ratio (OSNR) and overall DMG after 8-stage transmission are respectively 13.89 dB and 1.59 dB, which may theoretically support 1000 km-long transmission of 100 Gb/s DP-QPSK signal. A cascade amplification system composed of six-mode EDFA with the DMG of 1.35 dB is also considered to verify the feasibility of the equivalent input spectrum method.

A Low Noise Variable Gain Amplifier with 97.2 dB Linear Gain Range for CW Radar

This manuscript reports the design of a low noise variable gain amplifier (VGA) having wide dB linear gain characteristics for a continuous wave (CW) radar. A pseudo-exponential gain control function has been adopted in this VGA for the wide dB-linear behavior. Also, a BJT-based gain stage has been proposed to improve the gain dynamic range and low noise performance due to its higher transconductance/gain and lower flicker noise contribution. This proposed 2-gain stage VGA has been implemented in 130 nm SiGe bipolar complementary metal–oxide–semiconductor (BiCMOS) technology. This design performance has been benchmarked by post-layout simulation results. It has demonstrated a voltage-controlled gain from -33.6 dB to 74.4 dB (total 108 dB), with a 97.2 dB linear gain range, input referred noise of 2.4 nV /√Hz, and power consumption of 4.25 mW. This VGA has a 3-dB bandwidth of 10 MHz at a maximum gain of 74.4 dB and 251 MHz at a minimum gain of -33.6 dB with a chip layout area of 0.0682 mm2 . Compared to the latest available CMOS/BiCMOS VGAs in the literature, this proposed VGA has the highest gain dynamic range and dB-linear gain range with minimum input referred noise simultaneously across the operation bandwidth.

Optimization of osmotic dehydration of orange pieces (valencia late) in sugar solution using response surface methodology

Response surface methodology was used to determine the optimum processing conditions that yield maximum water loss and weight reduction and minimum solid gain during osmotic dehydration orange pieces (valencia late) in sugar solution using response surface. The experiments were conducted according to a Central Composite Design ‘CCD’. The independent process variables for osmotic dehydration process were temperature (40, 50, 60 °C), processing time (60, 120 et 240 min) and sugar concentrations (45, 55, 65 % w/w). The optimal conditions for maximum water loss, weight reduction and solid gain (candying) correspond to temperature of 50 °C, processing time of 240 min, sugar concentration of 65 % in order to obtain water loss 60.83 % (g/100 g fresh sample), solid gain of 46,48 % (g/100 g fresh sample) and weight reduction of 57.42 (g/100 g fresh sample). However the optimal conditions for maximum water loss and weight reduction and minimum solid gain (respectively 53.28 %, 57.88 % and 27.18 %) correspond to temperature of 40 oC, processing time of 240 min, sugar concentration of 65 %.

An S-band MMIC LNA in GaAs 0.15-μm pHEMT

The study adopts a monolithic microwave integrated circuit (MMIC) low-noise amplifier (LNA) applied in S-band was designed using ADS simulation software, GaAs 0.15-um pseudomorphic high electron mobility transistor (pHEMT) process. The LNA small signal gain is greater than 30.8 dB, gain flatness is ±0.45 dB, noise coefficient is less than 1.5 dB, input and output return loss is greater than 10 dB, and the chip area is 1.2*2.4 mm2. The low noise amplifier is composed of a two-stage cascade structure. Gain flatness, gain control, and bandwidth broadening are improved by RLC negative feedback network. The minimum noise coefficient circle and maximum gain circle are narrowed by adding negative feedback to achieve better noise coefficient and gain.

Exploiting NOMA and RIS in Integrated Sensing and Communication

A novel integrated sensing and communication (ISAC) system is proposed, where a dual-functional base station is utilized to transmit the superimposed non-orthogonal multiple access (NOMA) communication signal for serving communication users and sensing targets simultaneously. Furthermore, a new reconfigurable intelligent surface (RIS)-aided-sensing structure, where a dedicated RIS is deployed to provide virtual line-of-sight (LoS) links for radar targets, is also proposed to address the significant path loss or blockage of LoS links for the sensing task. Based on this setup, the beampattern gain at the RIS for the radar target is derived and adopted as a sensing metric. The objective of this paper is to maximize the minimum beampattern gain by jointly optimizing active beamforming at the base station (BS), power allocation coefficients among NOMA users and passive beamforming at the RIS. To tackle the non-convexity of the formulated optimization problem, the beampattern gain and constraints are first transformed into more tractable forms. Then, an iterative block coordinate descent (IBCD) algorithm is proposed by employing successive convex approximation (SCA), Schur complement, semidefinite relaxation (SDR) and sequential rank-one constraint relaxation (SRCR) methods. To reduce the complexity of the proposed IBCD algorithm, a low-complexity iterative alternating optimization (IAO) algorithm is proposed. Particularly, the active beamforming is optimized by solving a semidefinite programming (SDP) problem and the closed-form solutions of the power allocation coefficients are derived. Numerical results show that: i) the proposed RIS-NOMA-ISAC system always outperforms the RIS-ISAC system without NOMA in beampattern gain and illumination power; ii) the low-complexity IAO algorithm achieves a comparable performance to that achieved by the IBCD algorithm. iii) high beampattern gain can be achieved by the proposed joint optimization algorithms in underloaded and overloaded communication scenarios.

Optimizing the water absorption behaviour and natural weathering resistance of compatibilized ironwood-based recycled polypropylene composites

This study focused on the optimization of material resistance of wood-plastic composite (WPC) made using recycled polypropylene and industrial ironwood residues toward water and natural weathering exposure. The Taguchi method was employed to optimize the WPC composition and manufacturing process parameters based on the L9 orthogonal array experimental design. The WPC specimens were prepared using two-step of extrusion compounding and compression moulding. As input process parameters, ironwood content, coupling agent content, moulding temperature, and pressure holding time have been taken into consideration. The results were then optimized to get the maximum tensile properties of strength and modulus of elasticity as well as minimum water-weight gain and discolouration area after exposure to water immersion and natural weathering. The grey relational analysis (GRA) was carried out to identify the most significant factors and optimal levels that work synergistically to produce enhanced results. For optimizing the performance after water uptake, the ironwood content and moulding temperature are the most significant parameters with percentage contributions of 48.71% and 43.16%, respectively. Meanwhile, the multi-objective optimization technique of GRA obtains that ironwood content is the most significant factor for optimizing the mechanical and physical performance of the WPC after exposure to natural weathering with a percentage contribution of about 71%. Considering the good resistance of the material toward environmental exposure, this study opens up a pathway to effectively utilize ironwood and recycled polymer waste as a sustainable composite material in outdoor applications.

Modeling and numerical simulation optimization for minimizing the gain spectrum of bismuth-doped broadband fiber amplifiers at 1200-1800 nm

Research on optical fiber amplifiers has gotten much more in-depth in recent years as a direct result of the emergence of the information age. The most effective of these materials are optical fibers that have been doped with rare earth elements. Lasers that have gain media composed of rare-earth doped optical fibers find widespread use in fields such as optical communication, medicine, and the processing of materials. For different rare earth ions, especially for bismuth-doped fiber amplifiers, bismuth-doped fiber has a good prospect in fiber amplifiers and lasers due to its unique luminescence characteristics and ultra-wideband near-infrared luminescence of bismuth. Therefore, for bismuth-doped fiber amplifiers, in this paper, the pump wavelength is designed for the signal wavelength range, energy level structure, and electron transition process. The corresponding rate equation and power equation are established. At the same time, the gain spectrum changes with the fiber length and doping concentration are calculated using Matlab programming, and the maximum and minimum gain differences are minimized using Matlab calculations.

Impact of land tenure security through customary law on agricultural productivity in Burkina Faso: Propensity score matching approaches

Land tenure security plays an important role in agricultural production systems. The objective of this paper is to empirically assess the impact of land tenure security through customary law on agricultural productivity in Burkina Faso. We use panel data from 15,627 agricultural households over the period 2019–2021. Four propensity score matching methods are used: the nearest neighbor method, the stratification method, the radius method and the kernel method. The instrumental variables technique was used to control for endogeneity. Overall, the results indicate that household land security improves agricultural productivity. The minimum gain in agricultural productivity is estimated to be USD 86.4 per agricultural asset per season for households with customary land tenure. In terms of economic policy implications, the results call on the authorities in charge of conducting agricultural policies to promote comprehensive land policies by adapting them to local contexts through the recognition of customary institutions for rural land management.

Design and construct a Yagi Antenna with Three Reflector Element to Strengthen 4G Signal in Rural Areas

Rural areas are indicated to be still difficult to reach by 4G signals due to diverse topographical conditions and uneven landscapes, especially hilly areas that weaken the signal reception level in this region. To make the 4G signal accessible in this area, a repeater in the form of an antenna is needed to strengthen the signal. In this study, a yagi antenna is designed with three reflector elements at a working frequency of 1800 Mhz 4G LTE, expected to produce a minimum gain of 12 dBi and a more focused antenna radiation to strengthen the 4G signal in rural areas. The antenna design was simulated using CST Studio Suite software, with optimized simulation results yielding a return loss of -22 dB, VSWR 1.167, and gain 12.40 dBi. From the measurements obtained, the yagi antenna with three reflector elements works well at a frequency of 1800 Mhz, with a return loss of -34.77 dB, VSWR 1.065, gain 12.96 dBi, and unidirectional radiation. With the optimal antenna parameters and the addition of three reflector elements, it's possible to increase the gain value, even though the gain increase isn't substantial, and it narrows the HPBW (Half Power BeamWidth) value. Moreover, testing the yagi antenna at 3 different distances demonstrated that the resulting gain value can enhance 4G signal speed in rural areas

Multi‐agent reinforcement learning based transmission scheme for IRS‐assisted multi‐UAV systems

AbstractIn this paper, a transmission scheme based on multi‐agent reinforcement learning for intelligent reflecting surface (IRS)‐assisted multiple unmanned aerial vehicles (UAVs) systems is proposed. The proposed scheme is based on reinforcement learning and alternating optimization algorithm, which can effectively improve communication quality and ensure fairness. The scheme is divided into two parts. In the first part, the multi‐UAV cooperation problem is modeled as a markov decision process. The objective of each UAV is to maximize the minimum user channel gain. To achieve stable strategies for all agents, the Multi‐agent Deep Deterministic Policy Gradient (MADDPG) algorithm is applied to train UAVs trajectories to reach the Nash equilibrium. The MADDPG algorithm is centralized trained at the base station and executed in a distributed manner by each UAV, ensuring efficient and effective coordination among agents. In the second part, an alternating optimization algorithm is formulated to optimize active and passive beamforming. Considering the non‐convexity of the fairness objective, by using auxiliary variables and semi‐definite relaxation method, the problem of maximizing the minimum user achievable rate is transformed into a feasibility problem. Simulation results show that the proposed scheme can effectively train UAVs trajectories and improve the communication performance of all users fairly.

A Nonlinear Optimization Design Algorithm for Nearly Linear-Phase 2D IIR Digital Filters

In this paper, a new optimization method for the design of nearly linear-phase two-dimensional infinite impulse (2D IIR) digital filters with a separable denominator is proposed. A design framework for 2D IIR digital filters is formulated as a nonlinear constrained optimization problem where the group delay deviation in the passband is minimized under prescribed soft magnitude constraints and hard stability requirements. To achieve this goal, sub-level sets of the group delay deviations are utilized to generate a sequence of filters, from which the one with the best performance is selected. The quality of the obtained filter is evaluated using three quality factors, namely, the passband magnitude quality factor Qh and the group delay deviation quality factor Qτ, while the third one is a new quality factor Qs that assesses the performance in the stopband relative to the minimum filter gain in the passband. The proposed framework is implemented using the interior-point (IP) method in a MATLAB environment, and the experimental results show that filters designed using the proposed method have good magnitude response and low group delay deviation. The performance of the resulting filters is compared with the results of other methods.

An improved WiFi sensing based indoor navigation with reconfigurable intelligent surfaces for 6G enabled IoT network and AI explainable use case

The expanding number of low cost sensors and smart devices drives the internet-of-things (IoT) ecosystem of the future. These sensing devices are connected to the internet for information exchange. The location and positioning of these nodes is very important information required in vast range of location based services like smart homes, smart healthcare, environmental monitoring, personal navigation and smart transportation. This paper presents an intelligent solution for node localization in a 6G enabled IoT network. An indoor communication network scenario is proposed in which reconfigurable intelligent surfaces (RISs) are installed to locate the sensor nodes operating in that network. The performance evaluation of the proposed scheme is carried out with optimum number of reflecting elements and optimum phase shifts. It is observed that optimized RISs with 100 reflecting elements improve the estimated localization error by 7.4% over non-optimum RISs. Also, the minimum gain of 6% in localization error is offered using equal phase shifts over random phase shifts. Further, the effect of channel conditions on the average estimation error in node locations is also elaborated. In the end, the explainable artificial intelligence (XAI) empowered indoor localization is discussed as a use case scenario and the performance comparison of the algorithms is evaluated.

Play Call Strategies and Modeling for Target Outcomes in Football

This article considers one-off actions for a football coach who is asking for a specific outcome from a play. This will be in the form of a minimum gain in yards, usually in order to gain a first down. Using a random utility model approach we propose the play to be called is the one which maximizes the probability of the desired outcome. We specifically focus on pass plays, which requires the modeling of outcomes in terms of yards gained, for which we use the family of generalized gamma distributions. The data and results relate to the Fall 2021 Presbyterian College football team, in which we leverage specific information pertaining to the offensive playbook.

Investigation of flame and flow response in the swirler with different divergence cups and central body under external excitation

Effects of swirl divergence cup and the central bluff body on premixed flame response with external excitation are experimentally investigated. Flame transfer functions (FTFs) associated with different swirlers are measured in 50–450 Hz. The corresponding flame and flow responses are examined with the help of chemiluminescence images and Particle Image Velocimetry (PIV) method. Results show that FTF gain curves of swirlers with different divergence cups are characterized by alternating regions with first a minimum and then a maximum value as the excitation frequency increases. Increasing the divergence cup may greatly reduce the corresponding FTF minimum gain. Dynamic mode decomposition and proper orthogonal decomposition analysis indicate that flames with large divergence cup angles are dominated by the flame angle oscillations at the minimum gain point, while the flame with zero cup presents both the flame angle oscillations and vortex shedding. PIV results indicate that vortical structures located at the outer shear layer (OSL) could induce high-flame response, while the impacts of vortical structures located at inner shear layer are much weaker. Increasing the divergence cup could largely weaken the strength of vortical structures at OSL. In addition, effects of the central bluff body on flame response are significant. The flame in the swirler without the central bluff body is mainly governed by flame angle oscillations, and the elongated flame induced by the swirler with a large body is almost not sensitive to acoustic excitations. These results are useful for the understanding of flame response mechanisms in premixed swirling combustion.

Half-Height Pin Gap Waveguide-Based Slow-Wave Structure for Millimeter Wave Traveling-Wave Tubes

The design of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{W}$</tex-math> </inline-formula> -band traveling-wave tube (TWT) power amplifier based on a groove gap waveguide (GW) slow-wave circuit is presented in this article. The technology of GW is analyzed to aid the design of electromagnetic band gap-based slow-wave structures (SWSs) in the upper millimeter wave range of the spectrum while alleviating some of the typical fabrication challenges at these frequencies. The results of particle-in-cell (PIC) simulations numerically demonstrate a 10-GHz instantaneous 3-dB bandwidth in the range 89–99 GHz with a minimum power gain of 25 dB. A prototype of the complete SWS is manufactured via computer numerical control (CNC) machining and measured to verify the cold simulation results. Machining tolerances and surface roughness are also investigated. The design approach via groove GW is flexible and can be extended to alternative rectangular waveguide-based SWSs.

Gaussian Belief Space Path Planning for Minimum Sensing Navigation

In this article, we propose a path planning methodology for a mobile robot navigating through an obstacle-filled environment to generate a reference path that is traceable with moderate sensing efforts. The desired reference path is characterized as the shortest path in an obstacle-filled Gaussian belief manifold equipped with a novel information-geometric distance function. The distance function we introduce is shown to be an asymmetric quasi-pseudometric and can be interpreted as the minimum information gain required to steer the Gaussian belief. An RRT*-based numerical solution algorithm is presented to solve the formulated shortest-path problem. To gain insight into the asymptotic optimality of the proposed algorithm, we show that the considered path length function is continuous with respect to the topology of total variation. Simulation results demonstrate that the proposed method is effective in various robot navigation scenarios to reduce sensing costs, such as the required frequency of sensor measurements and the number of sensors that must be operated simultaneously.

Reconfigurable Intelligent Surface for FDD Systems: Design and Optimization

Reconfigurable intelligent surface (RIS) has recently emerged as a promising technology for wireless communications, which intelligently controls the phase shift of each unit cell to form desired beams. Most prior works on RIS consider time-division duplexing (TDD) systems, in which the same phase shifts can be applied to both uplink and downlink due to the channel reciprocity. However, for frequency-division duplexing (FDD) systems, using the same phase shifts will result in beam misalignment, thereby leading to performance degradation. To address this issue, in this paper, we study the practical RIS design and beamforming optimization for FDD systems. By representing the phase shifts of RIS with the equivalent circuit model which includes the resistance, inductances, and tunable capacitance, we propose a methodology to design the circuit parameters (i.e., inductances and capacitance) to meet the desired reflection requirements (i.e., phase tuning range, reflectivity, and zero phase slope) of both the uplink and downlink transmissions in FDD systems. Given the designed inductances, a practical binary RIS reflection model corresponding to two reflection states is then proposed. Furthermore, based on the proposed reflection model, a problem is formulated to jointly optimize the active and passive beamforming such that the minimum array response gain of the uplink and the downlink is maximized. An efficient iterative algorithm is proposed to obtain a suboptimal solution. Simulation results show that our proposed RIS design outperforms those benchmarks which design the circuits by only optimizing either uplink or downlink.

Model-less prediction filter for adaptive adjustment process noise.

In this study, a filtering scheme suitable for high-precision sensors was proposed to extract high-precision sensor information. According to the principle of Kalman gain based on data fusion, a model-less prediction filter with minimum gain measurement noise compensation and process noise posteriori constraint adjustment was developed. In comparison to various Kalman filter methods, the proposed algorithm demonstrated better accuracy in the steady state. The high precision performance and effectiveness of the model-less prediction filter were verified under a digitally controlled linear power supply.

Evaluation of a modular all-in-one high-resolution PET detector and readout electronics setup

Objective. The all-in-one solution and modularity of the C13500 series TOF-PET detector modules (Hamamatsu Photonics K.K., Hamamatsu, Japan) make them a highly attractive candidate for the development of positron emission tomography (PET) systems. However, the commercially available portfolio targets clinical whole-body PET systems with a scintillation crystal cross area of 3.1 × 3.1 mm2. To extend the modules for high resolution (preclinical or organ specific) systems, the support for smaller scintillation crystals is required. Approach. In this work, a PET detector was developed based on the TOF-PET modules using a light sharing approach, 16 × 16 lutetium oxyorthosilicate (LSO) scintillation crystals with a size of 1.51 × 1.51 × 10.00 mm3 readout with 8 × 8 photosensor channels of size 3.0 × 3.0 mm2. In addition to hardware and software development, the optimized parameter settings for the adapted configuration were evaluated. Main Results. A factor of two in amplification of the analog signal compared to the minimum gain setting was necessary for an accurate crystal identification (peak-to-valley ratio 14.9 ± 5.9). A further increase to a factor of three was not determined as optimum as the time over threshold duration, thus pile-up probability, increased from 1032.1 ± 109.5 to 1789.5 ± 218.5 ns (photopeak position). With this amplification a full width at half maximum (FWHM) energy resolution of 14.1 ± 2.0% and a high linearity of the energy detection was obtained. A FWHM coincidence resolving time (CRT) of 313 ps was achieved by using a low timing threshold, increasing the bandwidth of the front-end circuit and using a narrow ± 1σ energy window. To approximately double the sensitivity and reduce the power consumption, the timing parameters were adjusted resulting in a FWHM CRT of 354 ps (±2σ). Significance. Based on the results obtained with the proof-of-concept detector setup, we confirm the modularity and flexibility of the all-in-one TOF-PET detector modules for the future development of application-specific high-resolution PET systems.