A novel algorithm for maximum power point tracking using computer vision (CVMPPT).

The behavior of an illuminated solar module can be characterized by its power-voltage curve. Tracking the peak of this curve is essential to harvest the maximum power by the module. The position of the peak varies with temperature and irradiance and needs to be traced. Under partial shading conditions, the number of peaks increases and makes it more difficult to find the global maximum power point (MPP). Various methods are used for maximum power point tracking (MPPT) that are based on iterations. These methods are time-consuming and fail to work satisfactorily under rapidly changing environmental conditions. In this paper, a novel algorithm is proposed that for the first time, utilizes computer vision to find the global maximum power point. This algorithm, which is implemented in Matlab/Simulink, is free of voltage iterations and gives the real-time data for the maximum power point. The proposed algorithm increases the speed and the reliability of the MPP tracking via replacing analogue electronics calculations by digital means. The validity of the algorithm is experimentally verified.

Physical and psychological workloads and their association with occupational fatigue among hospital service personnel.

BACKGROUND: Physical and psychological workloads are a vital issue in the workplace. This study aimed to investigate the association between physical and psychological workloads and occupational fatigue among Iranian hospital service personnel. In Iran, hospital service personnel refers to a group of healthcare workers who undertake a range of duties, such as moving and carrying the hospital waste, transporting patients by wheelchair or gurney to the operating room, x-ray department, other wards, or other locations around the facility, performing cleaning tasks such as changing linens, mopping floors, and sterilizing equipment, and following infection control procedures to reduce the risk of spreading germs within the hospital setting. METHODS: This cross-sectional study was conducted on 198 Iranian hospital service personnel. The response rate was 86%. The data were gathered using 1) The Persian version of the Job Content Questionnaire (P-JCQ) for assessing physical and psychosocial workloads and 2) The Persian version of the Swedish Occupational Fatigue Inventory (P-SOFI-20) for assessing fatigue dimensions. RESULTS: According to the P-JCQ, the physical and psychological workload intensities were high in 72.7% and 47% of the participants, respectively. Based on the P-SOFI, the participants' mean scores of "physical fatigue" (21.73 ± 6.2), "psychological fatigue" (13.61 ± 5.76), and "fatigue due to shift work" (18.17 ± 5.6) were moderate, while the mean score of "general fatigue" was high (27.3 ± 6.98). The findings revealed that various types of fatigue are associated with age, gender, marital status, daily working hours, and psychological workload. CONCLUSIONS: Psychological workload was a determinant of occupational fatigue among Iranian hospital service personnel. Hence, an interventional program, including job enrichment, job rotation, and work-rest cycle, is recommended.

Priming of postural training with cerebellar anodal transcranial direct current stimulation for its effects on postural balance and fear of falling in patients with multiple sclerosis: A randomized, double-blind, sham-controlled study.

Postural impairment is one of the most disorders in patients with multiple sclerosis (MS), while fear of falling can exacerbate it in these patients. One of the leading causes of postural impairment and fear of falling in patients with MS is the cerebellum region's abnormalities, which may be modulated by cerebellar anodal transcranial direct current stimulation (a-tDCS). The present study aimed to investigate the effects of cerebellar a-tDCS concurrent with postural training (cerebellar a-CSC-PT) on postureand fear of falling in patients with MS. Thirty-seven patients with MS were assessed to randomly assign into cerebellar a-tDCSC-PT, shamtDCSC-PT, and postural training alone groups. All groups received 10-session postural training, while 20-minute cerebellar a-tDCS was added in the tDCS groups. Before, immediately and one month after the intervention, posture, balance and fear of falling were assessed using Biodex Balance System, Berg Balance Scale (BBS), and Fall Efficacy Scale-International (FES-I), respectively. Postural stability indices, BBS, and FES-I scores improved immediately and one month after the intervention in the cerebellar a-tDCSC-PT group (p < 0.001). Postural stability indices were immediately improved after intervention in the control groups (P < 0.05), while the changes were not maintained one month after intervention (P > 0.05). However, FES-I was not changed after the intervention in the control groups (P > 0.05). Cerebellar a-tDCS induces the effects of postural training on posture and balance and controls the fear of falling. This knowledge helps the physicians/therapists plan tDCS interventions to improve the balance, posture, and fear of falling in MS patients.

An all-sputtered photovoltaic ultraviolet photodetector based on co-doped CuCrO2 and Al-doped ZnO heterojunction.

We propose and fabricate a heterojunction between Al-doped ZnO and (Mg, N)-doped CuCrO2 thin films using the sputtering deposition method. These materials possess wide bandgap that makes them transparent in the visible light but excellent UV-absorbers. On the other hand, the high conductivity of these materials, respectively as n-type and p-type transparent conducting oxides, facilitates the charge transport. We show that the p-n junction fabricated from these materials has the potential to act as a high-performance UV photovoltaic photodetector. The proposed structure, demonstrates fast responses in order of sub seconds, photosensitivity of ~ 41,000, responsivity of 1.645 mA/W, and a detectivity of 3.52 × 1012 Jones that are significantly improved in comparison with the Al-doped ZnO photoconductor. This excellent improvement is attributed to the capability of the photovoltaic configuration that creates a built-in voltage and facilitates the charge separation and collection rather than recombination in the photoconductor configuration.

High-Voltage, High-Current Electrical Switching Discharge Synthesis of ZnO Nanorods: A New Method toward Rapid and Highly Tunable Synthesis of Oxide Semiconductors in Open Air and Water for Optoelectronic Applications.

A novel method of oxide semiconductor nanoparticle synthesis is proposed based on high-voltage, high-current electrical switching discharge (HVHC-ESD). Through a subsecond discharge in the HVHC-ESD method, we successfully synthesized zinc oxide (ZnO) nanorods. Crystallography and optical and electrical analyses approve the high crystal-quality and outstanding optoelectronic characteristics of our synthesized ZnO. The HVHC-ESD method enables the synthesis of ZnO nanorods with ultraviolet (UV) and visible emissions. To demonstrate the effectiveness of our prepared materials, we also fabricated two UV photodetectors based on the ZnO nanorods synthesized using the subsecond HVHC-ESD method. The UV-photodetector test under dark and UV light irradiation also had a promising result with a linear ohmic current-voltage output. In addition to the HVHC-ESD method's excellent tunability for ZnO properties, this method enables the rapid synthesis of ZnO nanorods in open air and water. The results demonstrate the preparation, highlight the synthesis of fine hexagonal-shaped nanorods under a second with controlled oxygen vacancies, and point defects for a wide range of applications in less than a second.

Is the Acute and Short-Term Effect of Whole-Body Vibration the Same on the H-Reflex Recruitment Curve and Agility?

CONTEXT: Despite the widespread use of whole-body vibration (WBV), especially in recent years, its neurophysiological mechanism is still unclear and it is yet to be determined whether acute and short-term WBV exposure produce neurogenic enhancement for agility. OBJECTIVE: To compare the acute and short-term effects of WBV on the H-reflex-recruitment curve and agility. DESIGN: Cross-over study. SETTING: Clinical electrophysiology laboratory. PARTICIPANTS: 20 nonathlete male volunteers (mean age 24.85 ± 3.03 y). MAIN OUTCOME MEASURES: Subjects were randomly divided into 2 groups, H-reflex and agility. In the sham protocol, subjects stood on the turned-off vibration plate while maintaining the semisquat position, and then, after a 2-wk washout, vibration-training sessions were performed in the same position with a frequency of 30 Hz and an amplitude of 3 mm. H-reflex-recruitment curve was recorded and the agility test of a shuttle run was performed before and after the first session and also 48 h after the 11th session in both sham and vibration-training protocols. RESULTS: Acute effects of WBV training caused a significant decrease of threshold amplitude and H-max/M-max (P = .01 and P = .04, respectively). Short-term WBV training significantly decreased the threshold intensity of the soleus H-reflex-recruitment curve (P = .01) and caused a decrease and increase respectively, in the threshold intensity and the area under the recruitment curve. CONCLUSIONS: The results suggest an inhibitory effect of acute WBV training on the H-reflex response.

In vitro clearance and hemocompatibility assessment of ultrathin nanoporous silicon membranes for hemodialysis applications using human whole blood.

BACKGROUND/AIMS: Recent advances in nanotechnology have made it possible to mass-produce ultrathin silicon membranes with pore sizes in the range of nanometers. In this study, we investigate the possibility of employing ultrathin nanoporous silicon membranes with pore diameters of 5 and 20 nm for dialysis of human whole blood by performing in vitro clearance and hemocompatibility assessments. METHODS: A mini blood dialyzer is fabricated by mounting nanoporous silicon membranes on a Teflon structure. Clearance is calculated based on the concentration of sodium, chloride, ionized calcium, total CO2, glucose, creatinine and hematocrit measured before and after dialysis. Blood activation is assessed by flow cytometry. RESULTS: Blood contact with the nanoporous membranes induces considerable leukocyte activation. Coating of the membranes with polyethylene glycol significantly improves hemocompatibility without blocking the nanopores. CONCLUSION: Silicon nanoporous membranes are potential candidates for fabrication of miniaturized blood dialyzers. Their mechanical strength and hemocompatibility can be further improved.

Fabrication and characterization of a radiation sensor based on bacteriorhodopsin.

Available techniques of X-ray detection have been under development due to specific shortcomings such as finite lifetime, low sensitivity, and post-processing requirements. Here we report on the fabrication of an X-ray sensor based on bacteriorhodopsin (BR) with a radius of r=3mm as the sensing area on a flexible substrate. The flexible X-ray detector can be placed on the targeted area for real-time monitoring of radiation dosage. We show that BR sensor is a potential candidate for such a powerful sensing device. For this purpose, we measure the electrical current generated by the BR sensor under different radiation dosages, energies and dose rates. This averaged current is in the range of nanoampere and is proportional to the dose rate of the received X-ray. The current also increases with the increase of radiation energy. BR radiation sensor can be readily miniaturized and is relatively easy to fabricate. The capability for real-time data collection and reusability are other advantages of this radiation sensor.