Balanced Output Research Articles

Fluid balance in the resorption stage correlates with outcomes of severe burn patients

ObjectiveThe resorption stage is an important period involving early anti-shock treatment for severe burn patients. We aimed to investigate the quantitative variability in fluid balance during the resorption stage in severe burn patients, and to study its effect on patient outcomes. MethodsWe conducted a single-centre retrospective study of 100 severe burn patients with involvement of > 50% total body surface area (TBSA). We extracted clinical data on demographics, clinical characteristics and outcomes; calculated the daily net fluid balance (difference between fluid intake and fluid output) and daily fluid intake/output within one week after injury; and analysed the association between fluid balance and functional outcomes and prognosis. The relative volume (ml/kg/TBSA) was used for the determination of daily fluid volume in this study. ResultsThe daily net fluid balance (ml/kg/TBSA) of the deceased patients on the 4th, 5th, 6th, and 7th days after injury was higher than that of the surviving patients, but the opposite trend was found for the daily fluid output (ml/kg/TBSA). The partial correlation test showed that in the resorption stage of severe burn patients, fluid output was negatively correlated with the index levels of renal function and liver function, CRP level, blood lactic acid (LA) level, frequency of ventilator treatment, and capillary leakage index (CLI), but net fluid balance showed a completely opposite correlation. Moreover, fluid intake was negatively correlated with the index level of renal function and LA level, but positively correlated with the frequency of ventilator treatment. Furthermore, the logistic regression analysis showed that the net fluid balance and fluid output on Day 6 post-injury were independent risk factors for prognosis. ConclusionThis study suggested that greater fluid output in the resorption stage of severe burn patients was closely related to better outcomes, in addition, a gradually decreasing, lower positive net fluid balance may contribute to the improvement of functional outcomes, which will provide useful information for early fluid management and further prospective clinical study of severe burns.

Linewidth Narrowing of a Dual Wavelength-Selectable, Ring Cavity Erbium-Doped Fiber Laser Using a Saturable Absorber

The narrow linewidth fiber laser is useful in applications such as fiber sensing, optical communications, and spectroscopy. This paper presents an investigation of the model and an experiment of a stable, wavelength-selective, narrow linewidth, ring cavity erbium-doped fiber laser incorporating two fiber Bragg gratings (FBG) at 1530.18 nm and 1550.08 nm, respectively. An F-P tunable filter was used to select a specific wavelength after optimizing the spectral output from the two FBGs to measure their respective linewidths. The erbium-doped ring fiber laser was optimized by adjusting the optical cavity loss using a variable optical coupler at a coupling ratio of 95%. The variable coupler was set to an optimal coupling ratio of 95%, where the spectral output powers of 3.4 mW at 1530.18 nm and 3.1 mW at 1550.08 nm were achieved as the optimal fiber laser output powers. The balanced output power had an optical signal-to-noise ratio of (OSNR) of 61 dB for each wavelength. The linewidth was measured for both wavelengths without saturable absorbers, and 27.7 kHz and 28.3 kHz for 1530.18 nm and 1550.08 nm were obtained. Using the saturable absorber, the linewidths were narrowed to 25.3 KHz and 21.1 kHz for 1530.18 nm and 1550.08 nm, respectively.

Near-infrared-II balanced ambipolar phototransistors realized by the optimized planar-heterojunction channel layer and charge-transfer-complex photosensitive layer

Ambipolar organic phototransistors (OPTs) operating in the near-infrared II (NIR-II) were successfully fabricated by using an organic planar-heterojunction channel layer and an organic–inorganic charge-transfer-complex (CTC) photosensitive layer. After optimizations of the ratio of vanadium pentoxide in CTC hybrid system and the substrate temperature of the deposited channel layer, the devices shows the most balanced output characteristics in the dark and under 1310 nm light illumination. These OPTs yielded significantly enhanced currents upon infrared light illumination with the photoresponsivities as high as 0.115 A/W for the n-channel, and 2.600 A/W for the p-channel, respectively. By analyzing the energy band of the heterojunction structure, the operating mechanisms of the balanced ambipolar NIR-II OPTs were derived. This work will be helpful to design the ambipolar infrared phototransistor and brings forward design thought of realization of optical complementary MOS logic circuits in the future.

Radiation-balanced lasing in Yb3+:YAG and Yb3+:KYW.

Radiation-balanced lasing and thermal profiling is reported in two Yb-doped laser crystals at room temperature. In 3% Yb3+:YAG a record efficiency of 30.5% was achieved by frequency-locking the laser cavity to the input light. Both the average excursion and axial temperature gradient of the gain medium were maintained within 0.1 K of room temperature at the radiation balance point. By including saturation of background impurity absorption in the analysis, quantitative agreement was obtained between theory and the experimentally measured laser threshold, radiation balance condition, output wavelength, and laser efficiency with only one free parameter. Radiation-balanced lasing was also achieved in 2% Yb3+:KYW with an efficiency of 2.2% despite high background impurity absorption, losses from Brewster end faces that were not parallel, and non-optimal output coupling. Our results confirm that relatively impure gain media can be operated as radiation-balanced lasers, contrary to earlier predictions which ignored background impurity properties.

Impact of Household PV Generation on the Voltage Quality in 0.4 kV Electric Grid—Case Study

This article (case study) discusses the influence of household photovoltaic generation on the voltage quality in a three-phase 0.4 kV grid. The research analyzes remotely acquired data from two specially designed three-phase Y-connected power meters to understand the PV system’s influence on the grid. The values of the voltages, currents, THD, individual harmonics, power factor, and K-factor are obtained every 200 ms over several months, creating more than 20 GB of data. The loads are typical household electrical appliances and EV portable chargers. The main conclusion after analyzing the measurements is that three-phase PV generation in the presence of household loads can create or increase grid unbalance; important current values into the neutral wire and THD and K-factor increase in some cases. The results also uncovered that without current sensing at the household connection point to the three-phase grid to control the PV inverter, the balanced phase output power of the grid-tied inverter is harmful to the 0.4 kV grid balance.

ETIOLOGY, TREATMENT, AND OUTCOME OF POST-OPERATIVE ENTEROCUTANEOUS FISTULAE: A PROSPECTIVE STUDY

Background: Approximately 75% of enterocutaneous stula (ECF) occur following surgery. Due to the high morbidity and mortality associated with ECF, prompt and effective treatment is important. Objectives: To study the outcome and management of patients with enterocutaneous stula. Methods: Total 50 patients developing the enterocutaneous stula following surgery were included. All patients were treated either conservatively or operatively by various means and varying period of time. Treatment was focused on the correction of dehydration, controlling sepsis, management of electrolyte imbalance and nutritional support. Results: out of 50 patients mean age was 39.20±20 years. The study was male preponderance (70%). Around 62% of patients had small bowel stula (20 ileal, 6 duodenal, 5 jejunal) and 38% were large bowel stula. 72% patients had High-output stula. the most common complication was skin excoriation seen in 36% of patients followed by Intra-Abdominal Abscess (24%). 24% of skin excoriation was seen in high-output stula which was not signicant (p=0.33). 14% IAAwas seen in low output stula which was also not signicant. out of 50 patients 8 patients were died during follow up and 42 were recovered. Conclusions: Conservative management with emphasis on improvement of nutrition, control of sepsis, management of uid and electrolyte balance and control of stula output is rst line of management.

D-Band × 8 Frequency Multiplier Using Complementary Differential Frequency Doubler

A D-band <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 8$ </tex-math></inline-formula> frequency multiplier is presented in this letter. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 8$ </tex-math></inline-formula> frequency multiplier consists of two stages of the newly proposed common load complementary push-push doublers (CL-CPPDs) and one stage of NMOS push-push doubler. The proposed CL-CPPD uses a single load to generate a balanced output with high harmonic rejection (HR) and can be easily cascaded using transformers for a high multiplication ratio with low dc power consumption. The chip is fabricated by using a 40-nm CMOS technology, and it achieves a maximum output power of −2.48 dBm with an input power of 0 dBm in the frequency range of 131.2–144.8 GHz. All HRs are over 34 dBc in the frequency range of 131.2–144.8 GHz. The total dc power dissipation is 41.4 mW when supplied from a single voltage of 0.9 V and occupies 0.37 mm2 of the chip area.

The size of larval rearing container modulates the effects of diet amount and larval density on larval development in Aedes aegypti.

Mass-rearing of mosquitoes under laboratory conditions is an important part of several new control techniques that rely on the release of males to control mosquito populations. While previous work has investigated the effect of larval density and diet amount on colony productivity, the role of the size of the container in which larval development takes place has been relatively ignored. We investigated the role of container size in shaping life history and how this varied with density and food availability in Aedes aegypti, an important disease vector and target of mass-rearing operations. For each treatment combination, immature development time and survival and adult body size and fecundity were measured, and then combined into a measure of productivity. We additionally investigated how larval aggregation behaviour varied with container size. Container size had important effects on life history traits and overall productivity. In particular, increasing container size intensified density and diet effects on immature development time. Productivity was also impacted by container size when larvae were reared at high densities (1.4 larva/ml). In these treatments, the productivity metric of large containers was estimated to be significantly lower than medium or small containers. Regardless of container size, larvae were more likely to be observed at the outer edges of containers, even when this led to extremely high localized densities. We discuss how container size and larval aggregation responses may alter the balance of energy input and output to shape development and productivity.

Design of normally-off p-GaN/AlGaN/GaN heterojunction field-effect transistors with re-grown AlGaN barrier

In this paper, a novel p-GaN/AlGaN/GaN HFET with re-grown AlGaN is designed by using Silvaco TCAD. It demonstrates that a thin AlGaN barrier with relatively small Al content beneath the p-GaN positively shifts the threshold voltage and helps to obtain normally-off operation, while it also degrades the drain current obviously due to the low 2DEG concentration. On the other hand, the re-grown AlGaN barrier in the access regions can recover the 2DEG concentration and enhance the drain current partially. In addition, the field plate structure formed during the AlGaN re-growth process is beneficial to suppress the electric filed crowding and premature breakdown effectively under forward gate bias. By optimizing the device parameters, normally-off p-GaN/AlGaN/GaN HFET with balanced output current, threshold voltage and breakdown voltage is designed.

Perioperative changes in fluid distribution and haemodynamics in acute high-risk abdominal surgery

BackgroundUnderstanding the pathophysiology of fluid distribution in acute high-risk abdominal (AHA) surgery is essential in optimizing fluid management. There is currently no data on the time course and haemodynamic implications of fluid distribution in the perioperative period and the differences between the surgical pathologies.MethodsSeventy-three patients undergoing surgery for intestinal obstruction, perforated viscus, and anastomotic leakage within a well-defined perioperative regime, including intraoperative goal-directed therapy, were included in this prospective, observational study. From 0 to 120 h, we measured body fluid volumes and hydration status by bioimpedance spectroscopy (BIA), fluid balance (input vs. output), preload dependency defined as a > 10% increase in stroke volume after preoperative fluid challenge, and post-operatively evaluated by passive leg raise.ResultsWe observed a progressive increase in fluid balance and extracellular volume throughout the study, irrespective of surgical diagnosis. BIA measured variables indicated post-operative overhydration in 36% of the patients, increasing to 50% on the 5th post-operative day, coinciding with a progressive increase of preload dependency, from 12% immediately post-operatively to 58% on the 5th post-operative day and irrespective of surgical diagnosis. Patients with overhydration were less haemodynamically stable than those with normo- or dehydration.ConclusionDespite increased fluid balance and extracellular volumes, preload dependency increased progressively during the post-operative period. Our observations indicate a post-operative physiological incoherence between changes in the extracellular volume compartment and inadequate physiological preload control in patients undergoing AHA surgery. Considering the increasing overhydration during the observational period, our findings show that an indiscriminate correction of preload dependency with intravenous fluid bolus could lead to overhydration.Trial registration clinicaltrials.gov. (NCT03997721), Registered 23 May 2019, first participant enrolled 01 June 2019.

Iodine electron cyclotron resonance plasma source for electric propulsion

With the rapid development of commercial space in recent years, the low-power and low-cost propulsion systems are needed more and more urgently. Compared with conventional chemical propulsion, electric propulsion has a higher specific impulse. Compared with the conventional xenon propellant, iodine propellant that does not require high pressure storage, is cheap and close to the relative atomic mass and ionization energy of xenon. Electron cyclotron resonance source has the advantages of no internal electrode, low pressure ionization, high plasma density and compact structure, which is suitable for low power electric propulsion. Therefore, the study of low power iodine propellant electron cyclotron resonance plasma source is of great significance. In this study, a set of corrosion-resistant feed system with balanced and stable output of iodine vapor is designed. Then the iodine-corrosion-resistant electron cyclotron resonance thruster is designed completely. A corrosion-resistant coaxial cavity structure is used to feed the microwave to the thruster, and the channel magnetic field is changed into a cusped field to generate more electron cyclotron resonance (ECR) layers. Finally, the combined ignition experiment is successfully conducted, showing the first plasma source using electron cyclotron resonance to ionize iodine propellant that can be used for electric propulsion in the world. The analyses of experiments, static magnetic field, microwave electric field distribution show that the unstable plasma plume scintillation at low power and low flow is caused by the conversion between ordinary wave electron plasmon resonance heating mode and extraordinary wave electron cyclotron resonance heating mode. The decrease of ionization rate at a high flow rate is caused by electron loss, wall loss and electronegativity of iodine propellant. Based on this principle, an improvement scheme is proposed. The plasma source has no obvious damage after discharge, which indicates that it has the potential of long life. This work preliminarily proves that the low power electron cyclotron resonance electric propulsion scheme of low power iodine propellant is feasible.

Machine learning for surrogate process models of bioproduction pathways

Technoeconomic analysis and life-cycle assessment are critical to guiding and prioritizing bench-scale experiments and to evaluating economic and environmental performance of biofuel or biochemical production processes at scale. Traditionally, commercial process simulation tools have been used to develop detailed models for these purposes. However, developing and running such models can be costly and computationally intensive, which limits the degree to which they can be shared and reproduced in the broader research community. This study evaluates the potential of an automated machine learning approach to develop surrogate models based on conventional process simulation models. The analysis focuses on several high-value biofuels and bioproducts for which pathways of production from biomass feedstocks have been well-established. The results demonstrate that surrogate models can be an accurate and effective tool for approximating the cost, mass and energy balance outputs of more complex process simulations at a fraction of the computational expense.

Carrier Redistribution Pulsewidth Modulation for Five-Level Stacked Multicell Converter

This article presents a modified carrier redistribution pulsewidth modulation (CRPWM) method for the five-level stacked multicell converter (SMC). The proposed CRPWM method is modified by exchanging the arrangement of the carriers of phase disposition pulsewidth modulation (PDPWM). With the ingenious carrier arrangement, the proposed PWM technique equalizes the utilization of phase leg voltage redundancies corresponding to the charging and the discharging state of each floating capacitor during one switching period of all the switches. The proposed modulation strategy has the same harmonic performance of line-to-line voltage with PDPWM, while the switch utilization is the same as phase-shifted pulsewidth modulation (PSPWM). Therefore, the voltage balancing of floating capacitors is achieved during a minimum switching period even with the influence of load current change and inappropriate carrier ratio is considered. The modified CRPWM is analyzed in theory and the voltage balancing ability and output harmonics performance are compared with PSPWM and traditional CRPWM. Simulation and experimental results on the laboratory prototype five-level SMC confirm the validity of the proposed CRPWM technique.

Nordic survey on assessment and treatment of fluid overload in intensive care.

Fluid overload in patients in the intensive care unit (ICU) is associated with higher mortality. There are few randomized controlled trials to guide physicians in treating patients with fluid overload in the ICU, and no guidelines exist. We aimed to elucidate how ICU physicians from Nordic countries define, assess, and treat fluid overload in the ICU. We developed an online questionnaire with 18 questions. The questions were pre-tested and revised by specialists in intensive care medicine. Through a network of national coordinators. The survey was distributed to a wide range of Nordic ICU physicians. The distribution started on January 5th, 2022 and ended on May 6th, 2022. We received a total of 1,066 responses from Denmark, Norway, Finland, Sweden, and Iceland. When assessing fluid status, respondents applied clinical parameters such as clinical examination findings, cumulative fluid balance, body weight, and urine output more frequently than cardiac/lung ultrasound, radiological appearances, and cardiac output monitoring. A large proportion of the respondents agreed that a 5% increase or more in body weight from baseline supported the diagnosis of fluid overload. The preferred de-resuscitation strategy was diuretics (91%), followed by minimization of maintenance (76%) and resuscitation fluids (71%). The majority declared that despite mild hypotension, mild hypernatremia, and ongoing vasopressor, they would not withhold treatment of fluid overload and would continue diuretics. The respondents were divided when it came to treating fluid overload with loop diuretics in patients receiving noradrenaline. Around 1% would not administer noradrenaline and diuretics simultaneously and 35% did not have a fixed upper limit for the dosage. The remaining respondents 63% reported different upper limits of noradrenaline infusion (0.05-0.50 mcg/kg/min) when administering loop diuretics. Self-reported practices among Nordic ICU physicians when assessing, diagnosing, and treating fluid overload reveals variability in the practice. A 5% increase in body weight was considered a minimum to support the diagnosis of fluid overload. Clinical examination findings were preferred for assessing, diagnosing and treating fluid overload, and diuretics were the preferred treatment modality.

Changes in ecosystem nutrient pools through stand development following whole-tree harvesting of jack pine (Pinus banksiana) on sandy, nutrient poor soils in northern Lower Michigan

We used a 10-site, 42-year chronosequence of jack pine (Pinus banksiana) plantations to study the changes in ecosystem nutrient pools following whole-tree harvesting (WTH) on sandy soils. We developed locally-derived allometric equations to predict nutrient contents of jack pine as a function of diameter at breast height and used these to estimate the amount of nitrogen (N), calcium (Ca), potassium (K), magnesium (Mg), and phosphorus (P) stored in aboveground biomass. In addition, we quantified total N, Ca, K, Mg and P in surface organic horizons, plant-available nutrient pools in mineral soils and leaching losses of nutrients for four years post harvest. Finally, we constructed simple input–output nutrient balances accounting for harvest removals at varying ages, post-harvest leaching losses and nutrient inputs from atmospheric deposition and weathering under varying scenarios of harvest intensity and frequency. Nutrient accumulation in aboveground biomass followed a sigmoidal pattern with a period of rapid accumulation between ages 10–20 y, a period of slowing accumulation between 20 and 30 y to an apparent asymptote from 30 y onward. Our estimates of asymptotic aboveground nutrient stocks for these plantations were highest for N (263 kg ha−1), intermediate for K and Ca (112 and 95 kg ha−1) and lowest for Mg and P (22 and 17 kg ha−1). Nutrients in forest floor materials increased from our youngest stand (4 y post harvest) with no signs of slowing accumulation in older stands. We observed weak trends of increasing soil nutrient availability across our chronosequence; however, variability was high both within and among stands. The business-as-usual scenario of WTH and planting on a 50-y rotation had a positive input–output balance for all nutrients with the exception of K, where outputs over this rotation exceeded inputs by 54 kg K ha−1. Shifting to a bole-only harvest improved the nutrient balance for all elements considered and shifted K to a net positive balance of 32 kg K ha−1. Scenarios designed to maximize production of biomass energy with WTH on shorter rotations exacerbated the K imbalance, with net losses of 72 and 63 kg K ha−1 for 30- and 20-y rotations, respectively.

Endothelial mTOR Preserves Hematopoietic Stem Cell Fitness By Suppressing Thrombospondin1

Hematopoietic stem cells (HSC) reside in close proximity to blood vessels within the bone marrow (BM) termed 'perivascular niches' which provide instructive cues for maintaining HSC self-renewal potential. The perivascular niche is comprised of endothelial cells (ECs) lining the BM blood vessels (BMECs), and an array of perivascular stromal cells that collectively serve to regulate balanced HSC self-renewal and differentiation. While young HSCs are endowed with robust self-renewal potential, aging is associated with a significant decline in HSC fitness including a loss of their self-renewal ability and a biased differentiation towards the myeloid lineages at the expense of lymphopoiesis. These aging related HSC defects result in anemias, impaired response to immunizations, and an increased risk for developing clonal disorders including acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS). However, mechanisms that drive HSC defects during aging remain poorly understood, and represents a critical barrier towards developing strategies for preservation of hematopoietic fitness during aging. While HSC aging was generally assumed as a predominantly cell-intrinsic process, recent studies have identified that aging of the BM niche plays an instructive role in promoting age-related HSC defects. Supporting this, we recently discovered that aging is associated with a significant decline in mTOR activity within BMECs that impairs their capacity to serve as a HSC-supportive niche. Our findings showed that deletion of mTOR specifically within ECs of young (4 month old) mice (Endothelial Cell specific mTOR Knock Out; mTORECKO) is sufficient to recapitulate HSC aging phenotypes including loss of HSC self-renewal, and a myeloid-biased differentiation. Here, we sought to identify the mechanisms by which endothelial mTOR preserves HSC fitness. To identify candidate factors that promote HSC aging in mTORECKO mice, we performed a plasma proteomic analysis that revealed a putative role for Thrombospondin1 (Thbs1) wherein mTORECKO mice displayed elevated levels of Thbs1. Analysis of cultured BMECs revealed that inhibition of mTOR signaling within BMECs was sufficient to increase Thbs1 expression. Thbs1 is a well-defined antiangiogenic factor that has recently been identified to play a critical role in promoting a multitude of age-related cardiovascular and inflammatory disorders. However, whether Thbs1 regulates HSC activity is not known. To this end, we performed ex vivo HSC expansion transplantation assays which revealed that Thbs1 causes a significant decline in long term HSC engraftment. RNA Seq analysis of HSC expansions revealed that Thbs1 activates chronic inflammatory responses within HSCs that have been suggested to promote aging related HSC defects. To determine whether Thbs1 promotes HSC aging in mTORECKO mice, we crossed them with Thbs1 global knockout mice (Thbs1KO) to generate mTORECKOThbs1KO mice. Analysis of mTORECKOThbs1KO mice revealed that deletion of Thbs1 was sufficient to restore hematopoietic defects in mTORECKO mice including restoration of peripheral blood myeloid bias, BM HSC frequency and hematopoietic progenitor activity. Furthermore, serial HSC transplantation analysis confirmed that deletion of Thbs1 was sufficient to restore HSC self-renewal and lymphoid output in mTORECKO mice, identifying a putative role for Thbs1 as a pro-geronic factor for HSCs. To determine whether Thbs1 promotes HSC dysfunction during physiological aging, we aged Thbs1KO mice for 18 months and analyzed their hematopoietic parameters. Our analysis revealed that deletion of Thbs1 was able to prevent the age-associated increase in peripheral blood myeloid bias and BM HSC frequency. Notably, HSCs derived from aged (18 month old) Thbs1KO mice demonstrated a suppression of inflammatory responses by RNA Seq analysis, and a restoration of self-renewal ability and balanced lineage output in serial HSC transplantation assays, that are indistinguishable from HSCs derived from young (3 month old) mice. Our findings identify Thbs1 as a novel pro-geronic factor for HSC aging that can be targeted to preserve hematopoietic healthspan.

A miniature impact drive mechanism with spatial interdigital structure

The development of compact precision instruments has raised the growing demand for miniature actuators. However, most miniature actuators failed to achieve balanced output performances, which limits the functionality of compact precision instruments. In this paper, a novel miniature impact drive mechanism (IDM) with balanced output performances is proposed. It adopts a spatial interdigital structure, which is helpful to decrease the whole size. The structure design and working principle are discussed in detail. Then, an IDM prototype with a size of 10 mm × 9.7 mm × 8 mm is fabricated, and its output performances are characterized. Experiment results indicate that the prototype has high motion stability in both forward and reverse motions. The maximum speeds of forward and reverse motions are 1.81 mm/s and 2.45 mm/s, respectively. While the resolution of forward and reverse motions reaches 12.55 nm and 8.77 nm, respectively. Besides, the maximum self-locking and thrust forces achieve 904 mN and 167.9 mN, respectively. The study provides a novel design of miniature IDMs, which could be beneficial to advance their practical applications.

Comparison of back conversion and power differential in extra-cavity multi-optical parametric oscillator using MgO:APLN

The extra-cavity multi-optical parametric oscillator (MOPO) using MgO-doped aperiodically poled lithium niobite (MgO:APLN) is a technique to generate multi-wavelength tunable laser output, in which the back conversion and power differential can reduce the output power and conversion efficiency. A comparison of the back conversion and power differential between the two methods is presented in this paper. One approach is to adjust the mirror transmittance to change the parametric light's power density involved in the oscillation. With 1.47 μm transmittance of 20 % and 3.30 μm transmittance of 60 %, the 3.30 μm output power is 0.95 W, the 3.84 μm output power is 0.94 W, and the power ratio is 1.01. The other approach is to add two electro-optical polarization mode converters (EO PC) to change the parametric light's polarization. When the electric fields of two EO PCs are 66 V/mm and 15 V/mm, the 3.30 μm and 3.84 μm output powers are 2.54 W and 2.49 W, the conversion efficiencies are 10.3 % and 10.0 %, and the power ratio is 1.02. The comparison results confirm that both methods have the capability of back conversion suppression and power differential reduction. Compared with the adjusting transmittance, adding EO PCs has higher output power and conversion efficiency, which is the first reported method for better balanced multi-wavelength laser output.

Simulation Analysis of Graphene Addition on Polymeric Composite

Natural fibres in composite materials, such as kenaf fibres, are used to reinforce polypropylene (PP) due to their light weight and high mechanical performance required in various applications, such as automotive. Although natural fibres seem to be the most promising material, manufacturing parameters and material composition are crucial to determining balanced output performance. Therefore, this study provides essential knowledge on defining the parameters and the effect of addition of graphene content to kenaf fibres composites using computer simulation via Abaqus CAE software. Detailed analyses were compared with the experimental data of Young’s modulus and tensile strength. General static and dynamic explicit analyses were conducted using Abaqus CAE simulations, and set at 40 wt. % kenaf fibres, 0, 1, 3, and 5 wt. % graphene. Short kenaf fibres were utilised together with graphene nanoplatelets and prepared using a hot-pressing technique with the temperature set at 190 °C and pressure of 5 MPa for 5 min. The findings indicated that the simulation and experimental data from previous studies data congruent which is Young’s modulus and tensile strength increased with addition of graphene content. Thus, the simulated data could predict the experimental mechanical performance, in which 24 MPa of tensile strength was recorded for 3 wt. % of graphene additions.

Design of high-performance photovoltaic-thermoelectric hybrid systems using multi-objective genetic algorithm

Hybrid systems which integrate photovoltaic (PV) and thermoelectric generator (TEG) can improve the utilization of solar energy. In this study, a multi-objective genetic algorithm (MOGA) is adopted to maximize the output power and conversion efficiency for the PV-TEG system, where the CFD model is coupled in the optimization procedure and the penalty function is employed to ensure the appropriate operating temperature. Meanwhile, two geometric parameters along with two boundary conditions are selected as the design variables, while the effects of three cooling conditions are also discussed. Compared with the PV only system, the output power of the PV-TEG system is improved by up to 11.52% with the conversion efficiency also improved by 44.97%. At the same solar concentration condition, the optimal PV-TEG system could increase the output power by 36%. Based on the analysis of optimal solutions, it is demonstrated that the adopted TEG contributes significantly to the output power, while a better cooling condition also has a positive effect on the comprehensive performances. Furthermore, a multiple-criteria decision-making approach is applied to balance output power and conversion efficiency. Compared with the maximum efficiency solution, the best compromise solution increases output power by 120.02% and decreases the efficiency only by 14.83%.