Nighttime Operations Research Articles

SP9.11 - Characteristics and predictive factors associated with on table mortality in emergency laparotomy: insights from the National Emergency Laparotomy Audit

Abstract Aims Mortality during emergency laparotomy is a rare but significant event that can have a profound impact on patient’s families and the healthcare team. The aims of this study were to define the frequency of this occurrence within the National Emergency Laparotomy Audit (NELA) database and to investigate predictive factors. Methods All patients entered into the database between 2013-2020 were included. Multilevel logistic regression was used, with clinically important factors identified a a priori, to identify variables associated with intra-operative mortality. Results The overall incidence of intra-operative mortality was 1 in 400 cases (450/180,985). There was no difference in mortality rate between day-time and night-time operations. These patients presented critically unwell with signs of shock (50%, 225/450) and an ASA grade of ≥4 (76%, 343/450). Their baseline function status was good with a high proportion residing in their own home (97%, 437/450) and minimal signs of frailty. Acute mesenteric ischaemia was the indication for laparotomy for 46% of patients (207/450) and was associated with a threefold increase in the risk of intra-operative death (OR 2.97 (95% CI 2.35-3.75)). Other important predictive factors were hypotension at presentation (OR 1.56 (95% CI 1.22-1.99)) and a blood lactate of 4-6 (OR 3.89 (95% CI 2.62-5.76)). Conclusions Intra-operative mortality during emergency laparotomy is rare but remains a significantly higher occurrence than in other emergency surgical specialities. The strong association with acute mesenteric ischaemia necessitates optimisation of UK emergency department assessment pathways and more nuanced discussions about the risks of surgery in such high-risk patients.

Associations between 24/7 workforce coverage, organizational challenges, and well-being of emergency radiologists: a national survey.

The last decade has seen a surge in the demand for imaging exams in emergency radiology (ER), necessitating an evolution in organizational systems for departments offering round-the-clock care, while safeguarding patient care quality and physician well-being to prevent burnout. To develop a nationwide overview of ER organizations in France and identify structures that promote job satisfaction. Two surveys were sent to 709 radiological centers across France from March to June 2022, inquiring about organizational aspects and quality of life (QOL), incorporating four validated QOL questionnaires. The organization of each center was mapped, and correlations between respondent characteristics and mental health were analyzed using Pearson's and Wilcoxon tests. A total of 284 centers answered the organizational survey, with a response rate of about 41.6%. Among them, there were 32 university hospitals, 208 general hospitals, 2 teaching army hospitals, and 42 private facilities. Of these, night-time operations showed 14% on-site coverage, 12% on-call from home, 69% utilized external teleradiology, and 4% used in-house teleradiology. These trends persisted over weekends and holidays. Regarding the quality of working life, academic, general, and private radiologists are more satisfied with their practice compared to trainees. Depersonalization, part of the three dimensions of burnout, was high in every class, at 60% (n = 210/350). Outside of university hospitals, most radiology centers in France no longer have on-site radiologists during off hours. Residents are prone to lower job satisfaction and quality of life than more experienced radiologists. The survey illustrates how French ER is structured, pointing out the escalating significance of teleradiology and noting that radiologists generally experience high job satisfaction while also confronting typical organizational challenges. The need for continuous radiology coverage comes with unique logistical challenges, especially in ER. Night shifts show a significant reliance on teleradiology services, especially by external companies. Pay, shift patterns, and seniority affect the well-being of emergency radiologists, particularly the residents.

Does Timepoint of Surgical Procedure Affect the Outcome in Simultaneous Pancreas-Kidney Transplantation? A Retrospective Single-Center Analysis over 20 Years.

Background: Sleep deprivation and disturbances in circadian rhythms may hinder surgical performance and decision-making capabilities. Solid organ transplantations, which are technically demanding and often begin at uncertain times, frequently during nighttime hours, are particularly susceptible to these effects. This study aimed to assess how transplant operations conducted during daytime versus nighttime influence both patient and graft outcomes and function. Methods: simultaneous pancreas-kidney transplants (SPKTs) conducted at the University Hospital of Leipzig from 1998 to 2018 were reviewed retrospectively. The transplants were categorized based on whether they began during daytime hours (8 a.m. to 6 p.m.) or nighttime hours (6 p.m. to 8 a.m.). We analyzed the demographics of both donors and recipients, as well as primary outcomes, which included surgical complications, patient survival, and graft longevity. Results: In this research involving 105 patients, 43 SPKTs, accounting for 41%, took place in the daytime, while 62 transplants (59%) occurred at night. The characteristics of both donors and recipients were similar across the two groups. Further, the rate of (surgical) pancreas graft-related complications and reoperations (daytime 39.5% versus nighttime 33.9%; p = 0.552) were also not statistically significant between both groups. In this study, the five-year survival rate for patients was comparable for both daytime and nighttime surgeries, with 85.2% for daytime and 86% for nighttime procedures (p = 0.816). Similarly, the survival rates for pancreas grafts were 75% for daytime and 77% for nighttime operations (p = 0.912), and for kidney grafts, 76% during the day compared to 80% at night (p = 0.740), indicating no significant statistical difference between the two time periods. In a multivariable model, recipient BMI > 30 kg/m2, donor age, donor BMI, and cold ischemia time > 15 h were independent predictors for increased risk of (surgical) pancreas graft-related complications, whereas the timepoint of SPKT (daytime versus nighttime) did not have an impact. Conclusions: The findings from our retrospective analysis at a big single German transplant center indicate that SPKT is a reliable procedure, regardless of the start time. Additionally, our data revealed that patients undergoing nighttime transplants have no greater risk of surgical complications or inferior results concerning long-term survival of the patient and graft. However, due to the small number of cases evaluated, further studies are required to confirm these results.

Increased Metabolic Demand During Nighttime Walking in Hilly Forest Terrain While Wearing Night Vision Goggles.

Foot-borne soldiers sometimes carry out nighttime operations. It has previously been reported an elevated metabolic demand and impaired walking economy during outdoor walking on a gravel road in darkness wearing night vision goggles (NVG), compared with wearing a headlamp. The aim of the present study was to evaluate the effect of wearing NVG while walking in a hilly forest terrain and compare the results between experienced and inexperienced NVG users. At nighttime, two different groups, inexperienced (five men and six women) and experienced (nine men) NVG users, walked 1.1 km at a self-selected comfortable pace in a hilly forest. Part I was mainly uphill, and Part II was mainly downhill. Walks were performed wearing a headlamp (light), monocular NVG (mono), binocular NVG (bino), or mono with a 25 kg extra weight (backpack). Walking economy calculated from oxygen uptake in relation to body mass and covered distance (V̇O2 (mL/[kg · km])), heart rate, gait, and walking speed were measured. In both groups, walking economy was deteriorated in all three conditions with limited vision (mono, bino, and backpack) compared to the light condition, both during Part I (mono/bino, experienced: +26/+25%, inexperienced: +34/+28%) and Part II (mono/bino, experienced: +44/+46%, inexperienced: +63/+49%). In the backpack condition, the relative change of walking economy was greater for the inexperienced group than the experienced group: Part I (experienced: +46%, inexperienced: +70%), Part II (experienced: +71%, inexperienced: +111%). Concurrently, the step length was shorter in all three conditions with limited vision during Part I (mono/bino/backpack, experienced: -7/-7/-15%, inexperienced: -12/-12/-19%) and Part II (mono/bino/backpack; experienced: -8/-8/-14%, inexperienced: -17/-15/-24%) than in the light condition. The experienced NVG users walked faster during all conditions, but there was no difference in heart rate between groups. Despite that foveal vision using NVG is adequate, it appears that the mechanical efficiency during nighttime walking in hilly terrain was markedly lower while wearing NVG than with full vision, regardless of whether the soldier was an experienced or inexperienced NVG user. Moreover, the walking economy was even more affected when adding the 25-kg extra weight. It is probable that the deteriorated mechanical efficiency was partly due to the shorter step length in all three conditions with limited vision.

Free-space quantum key distribution during daylight and at night

Current satellite-based quantum key distribution (QKD) is limited to nighttime operations, and the reliance on microwave communication for key distillation leads to significant delays, often spanning several days. These challenges collectively hinder the establishment of a practical global-scale quantum network. Here, by developing a 625-MHz inherently robust decoy-state light source and daytime noise suppression close to the Fourier transform limitation, we achieve QKD covering all the 24 h of the day over a 20-km terrestrial free-space channel, resulting in an average secure key rate of approximately 495 bps. Additionally, bidirectional laser communication is integrated into the QKD transmitter and the ground station to enable real-time key distillation, improving the timeliness from days to real time. This comprehensive verification lays a solid foundation and paves the way for all-day real-time QKD with quantum satellites.

Fatigue Risk Management Preferences for Consumer Sleep Technologies and Data Sharing in Aviation.

INTRODUCTION: Employees from any type of aviation services industry were asked to give their opinions about the usefulness of consumer sleep technologies (CSTs) during operations and their willingness to share data from CSTs with their organizations for fatigue risk management purposes under a variety of circumstances.METHODS: Respondents provided information about position in aviation and use of CST devices. Respondents ranked sleep issues and feedback metrics by perceived level of importance to operational performance. Respondents rated their likelihood to share data with their organization under a series of hypothetical situations.RESULTS: Between January-July 2023, 149 (N = 149) aviation professionals responded. Pilots comprised 72% (N = 108) of respondents; 84% (N = 125) of all respondents worked short- or medium-haul operations. "Nighttime operations" and "inconsistent sleep routines" ranked as the most important issues affecting sleep. "Sleep quality history" and "projected alertness levels" ranked as most important feedback metrics for personal management of fatigue. Respondents were split between CST users (N = 64) and nonusers (N = 68). CST users did not indicate a strong preference for a specific device brand. The most-reported reason for not using a CST was due to not owning one or no perceived need. Respondents indicated greater likelihood of data sharing under conditions where the device was provided to them by their organization.DISCUSSION: These results suggest that aviation professionals are more concerned about schedule-related disturbances to sleep than they are about endogenous sleep problems. Organizations may be able to increase compliance to data collection for fatigue risk management by providing employees with company-owned CSTs of any brand.Devine JK, Choynowski J, Hursh SR. Fatigue risk management preferences for consumer sleep technologies and data sharing in aviation. Aerosp Med Hum Perform. 2024; 95(5):265-272.

Quantum BER estimation modelling and analysis for satellite‐based quantum key distribution scenarios

AbstractThe quantum communication channel is considered to be eavesdropped when the signal Quantum Bit Error Rate (QBER) exceeds a defined theoretical limit and is thus considered a figure of merit parameter for assessing the security of a quantum channel. This work presents a general mathematical model considering device imperfections and various sources of errors for estimating signal QBER in polarisation encoded satellite‐based QKD systems. QBER performance for satellite‐to‐ground downlink scenarios has been investigated for multiple sky brightness conditions (day time and night time operations), two operating wavebands: 800 and 1550 nm as well as for different quantum transmitter and quantum receiver architectures. Further, a novel QBER estimation analysis for inter‐satellite QKD links has also been presented. The estimation results obtained from the developed model have been validated against and found in good agreement with the measured results of the only reported satellite‐to‐ground QKD experiments till date. The presented QBER modelling and analysis will aid in system engineering and efficient design of future satellite‐based QKD systems.

Produced-Water Desalination Approach Uses Renewable Thermal Energy

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211175, “An Innovative Method of Water Management by Desalinating Produced Water Using Thermal Renewable Energy,” by Sharifa M. Al-Ruheili, Felix Tiefenbacher, and Khansaa H. Almahrami, ARA Petroleum Exploration and Production, et al. The paper has not been peer reviewed. _ The operator is adopting a method to manage high-salinity produced water in an environmentally sustainable way by extracting potable water from produced water and reducing discharge water volume by at least 50%. For desalination of the produced water, a combination of forward and direct osmosis technology is used. This process is driven mostly by thermal energy, which is provided to thermal collectors that are 100% solar. This technology uses renewable energy and will have no carbon footprint. Technology Description The technology involves concentrated solar thermal (CST) power plants that provide 100% renewable water desalination. Forward osmosis (FO) and direct osmosis (DO) can desalinate highly saline and polluted water, such as produced water, mainly with solar thermal energy. A pneumatic solar thermal plant consisting of two HELIOtube collectors, each 121 m long, provides the thermal energy for the desalination process. The plant includes a mirror technology based on CST, a cost-effective heat-transfer system using pressurized water as heat transfer fluid (HTF), and a low-maintenance thermal energy storage (TES) system allowing nighttime operations of 35 m3 volume with an operating temperature of 180°C using a pressurized water tank at 10-bar operating pressure. The desalination system will contain a pretreatment unit for the produced water and a desalination (FO) and brine-concentration (DO) unit. The unit will be integrated with thermal power to operate the desalination plant. In addition, a fully automated control system with a live backup will be installed. The system is classified as having low maintenance and cleaning costs because of its encapsulation features, rotatability of 300°, and convex shape. Fig. 1 of the complete paper shows the planned plant layout. The desalination plant will feature two outputs: fresh water of potable quality and brine. The fresh water will be used to serve the company’s freshwater demand, with excess water used for agricultural purposes or mixed with water in an injector well to improve injectivity. The other output, the highly concentrated brine (20% salt), will be collected in the existing evaporation pond where two main research and development studies are ongoing, one related to mineral extractions and the second related to salt monetization (using salt as a drilling additive).

Timing is everything; operational changes at a pumping station with a gravity sluice to provide safe downstream passage for silver European eels and deliver considerable financial savings

Catadromous European eel (Anguilla anguilla) are a critically endangered fish species due in part to in-river anthropogenic barriers (e.g., pumping stations, weirs, hydropower facilities). European legislation stipulates that safe downstream passage must be provided at hazardous intakes. Where present, gravity sluices have the potential to act as safe and low-cost downstream passage for seaward migrating silver eels at pumping station, but operational changes are required. This study used catchment-wide and fine-scale acoustic telemetry to investigate if operational changes (OC) at a pumping station (PS) with a co-located gravity sluice (GS) facilitated safe downstream passage for silver European eels. Specifically, night-time pump operations were ceased, river levels prior to sluicing were elevated and the GS was opened during key eel migration windows, i.e., at night during the new moon phase in autumn. No tagged eels passed through any pumps and the majority (2018 = 87.5%, 2020 = 88.9%) that approached the PS during OC passed downstream through the GS. Most eels approached during the first period of night sluicing after release (2018 = 73.9% and 2020 = 76.5%) and passed downstream during the first sluice event they experienced at the PS (2018 = 66.7% and 2020 = 75.0%). During the final approach prior to passage, very few retreats back upstream occurred at a median (IQR) distance of 34 (7.25) m from the GS and were predominantly a short distance (1–8 m). Overall, OC at a PS with a GS are considered a win-win-win, despite opening the sluice for <3% of the study period, given safe downstream passage was maximised, the financial benefits of sluicing water (∼£14,670 in direct operational costs over two years) and the relative ease of implementation.

Harvesting freshwater from atmospheric air using thermal energy storage enabled solar air heater

Fresh water resources are scarce worldwide, and prevailing water harvesting systems face limitations of nighttime operations, high regeneration temperature and limited water yield. To address such issues, a novel system that integrates thermal energy storage unit for harvesting fresh water from atmospheric air is built and experimentally investigated under the ambient conditions. The system includes 4.86 m2 both ends open evacuated tube collector solar air heater to produce high regeneration temperature. Additionally, it incorporates a standalone for water vapor condensation. The performance of the system is compared using two different solid desiccant materials based on energy, exergy, environmental and economic analyses. The system using silica gel harvests 3.75 L/day of fresh water at a cost of 0.13 $/L with water harvesting coefficient of 0.76, while from molecular sieve, 3.41 L/day was harvested at 0.15 $/L with water harvesting coefficient of 0.64. From silica gel, the system reported the maximum thermal, overall and exergy efficiencies of 62.22 %, 10.29 % and 2.31 %, respectively, while from molecular sieve it was 59.12 %, 9.53 % and 2.08 %, respectively. The reports of water sample confirm that the harvested water from both the desiccant materials is good and safe for domestic consumption.

Timing of Surgery and the Risk of Complications in Acute Appendicitis

Background: Delays surgery in patients with acute appendicitis there may be increase the risk of various complications. These risks must be balanced with the theoretical risk of night time operations. Objective: To evaluate the effect of time of surgery for acute appendicitis on surgical outcomes to optimize the timing of appendectomies. Materials and methods: This was a cross-sectional comparative study carried out in the Department of Surgery of Diabetic Association Medical college Hospital Faridpur from January 2016 to December 2021.The study population consisted of 400 patients who were diagnosed as acute appendicitis. They were separated in 2 groups according to timing of surgery, under 24 hours (group A) and 24 to 96 hours (group B) from the time of symptoms appear and had their rate of complications like perforation of appendix, post operative paralytic ileus, pelvic abscess, infection of surgical wound assessed. Result: One hundred forty patients underwent surgery less than 24 hours after symptoms appear (group A) and Two hundred sixty patients were operated between 24 to 96 hours of symptoms appearance. Groups A and B had significant difference regarding the complications. Conclusions: In our study, timing of surgery for acute appendicitis had great impact on the occurrence of complications.

Increased Metabolic Demand During Outside Walking in Darkness With No Vision or With Visual Aid.

For tactical reasons, the foot-borne soldiers sometimes undertake nighttime operations. However, the metabolic demand during walking in complete darkness may be markedly increased. The purpose of this study was to investigate if metabolic demand and kinematics would change while walking on a gravel road and a slightly hilly trail in darkness with or without visual aid. Fourteen cadets (11 men and 3 women, age: 25 ± 7 years, height: 178 ± 8 cm, and weight: 78 ± 13 kg) walked at 4 km/h on a straight gravel road and on a slightly hilly forest trail (n = 9). Both trials were performed at nighttime under four different conditions, wearing a headlamp (Light), blindfold (Dark), monocular (Mono), or binocular (Bino) night vision goggles. During the 10-minute walks, oxygen uptake, heart rate, and kinematic data were assessed. Ratings of perceived exertion, discomfort, and mental stress were evaluated after each condition using a category ratio scale. Physiologic and kinematic variables were evaluated using repeated-measures analysis of variance, whereas ratings were evaluated using non-parametric Friedman analysis of variance. Oxygen uptake was higher in all three conditions with no or limited vision (Dark, Mono, and Bino) than in the Light condition (P ≤ 0.02) when walking on both the gravel road (+5-8%) and the forest trail (+6-14%). Heart rate was higher during the Dark than during the Light condition when walking on the forest trail, whereas there was no difference between conditions on the gravel road. During both trials, gait frequency was higher during the Dark than during the Light, Mono, and Bino conditions. Ratings were generally low during all conditions. Walking on a gravel road or a forest trail wearing a blindfold or visual aid increased the metabolic demand. Thus, it appears that the metabolic demand is higher during overground walking with night vision goggles than with full vision, which may influence the performance of nighttime operations.

An experimental investigation of the effects of the number of capsules and operating conditions on the performance of encapsulated ice storage system

It is crystal clear to everyone that ice thermal energy storage (ITES) systems provide significant advantages in reducing cooling costs, balancing energy supply and demand profiles, and shaving the peak loads. When the thermodynamic performance of the ITES is compared with conventional AC, the following two points are critical: (i) ITES tends to increase the coefficient of performance (COP) of the system thanks to the lower ambient temperature during the nighttime (the charging period of ITES). (ii) It may cause a lower COP as a lower operating temperature is required to produce ice. In numerous papers, it has been reported that ITES can increase or decrease COP. This experimental study deals with the influences of the number of ice capsules and operating temperatures on the thermodynamic performance of the ITES-integrated cooling system. Results indicate that nighttime operation with the ITES provides higher COP and lower energy costs due to lower ambient temperature and no solar radiation. The highest COP value of the chiller is observed as 13.55. The highest COP during the charging period is found to be 8.99 when the storage medium is 0.3 m3, the charging temperature is −10 °C, and the ambient temperature is about 8 °C. The efficiency of discharging period is calculated to be 99.97 %. The best overall COP is observed to be 17.53 for the case at a storage medium volume of 0.3 m3 and a charging temperature of −12 °C. This is about three times higher than a conventional cooling system that works under ordinary daytime runs. Consequently, nighttime operations with ITES can reduce electricity consumption by 30 % and cooling costs by 62 %.

A review of a proposed noise quota system for Dublin Airport

In 2007, the airport authority for Dublin Airport (DAA) was granted planning permission to build a new runway. This permission included several planning conditions, including operating restrictions during the night-time due to noise considerations. The plans were then put on hold due to the economic downturn, but in 2016, with increasing passenger numbers, the plans were revived. In the intervening years, the planning and legislative environment related to aircraft noise changed in Ireland, particularly with the implementation of Regulation 598/2014 and the establishment of the Aircraft Noise Competent Authority (ANCA). Then, in December 2020 the DAA submitted a planning application to the Planning Authority seeking to amend those 2007 conditions associated with night-time operating restrictions. The application was referred to ANCA for an assessment of the associated noise impact, and in November 2021 they issued a draft regulatory decision report. This report proposes a number of mitigation measures for Dublin airport, including the introduction of a noise quota system. This paper reviews the proposed noise quota system.

Solar energy assisted thermal treatment model to decontaminate airborne viruses in hospital

• Thermal treatment model based on porous heating to decontaminate the airborne viruses in hospitals. • Solar parabolic collector and electric heaters are used to heat the infected air to abolish the virus. • An insulated chamber ascertains the requisite exposure period for complete decontamination. • The heat exchanger, storage tanks, and air-cooling system are anticipated for optimal cooling of the high-temperature decontaminated air. The evolution of airborne viruses across the globe has caused many deaths in recent decades. Currently, the world is witnessing the terrible behavior of SARS-CoV-2. The airborne viruses attached to the suspended air particles for a long time and spread rapidly. The dispersal of airborne viruses in the indoor air increases the risk of diseases. The present study endorses a solar-assisted heat treatment model to decontaminate airborne viruses and provide hospitals with disinfected air. A simplified model comprises the heating and cooling sections to abolish airborne viruses and cool the treated air. The heating section includes a solar parabolic trough collector (PTC)/electrical heater, porous domain, and decontamination chamber, while the cooling unit comprises storage tanks and an air cooler. A heat exchanger exchanges energy between hot and cold air streams. A solar PTC offers air heating during day time; however, the porous domain with the electrical heaters acts during the night and intermediate time. The airborne viruses can be abolished by passing through a porous domain and decontaminating chamber at 105 °C upholding an exposure period of 5 mins. The cooling section cools the disinfected air to comfortable conditions. A numerical analysis finds the optimal porosity of 0.9, owing to an exit temperature of 105 °C and a minimal pressure drop of 5.16 kPa. The high-temperature disinfected air leaving the storage tank (ST-2) further cools in an air cooler. Besides, the system’s energy efficiency is noted at 37.4 % and 91.1 % during daytime and nighttime operations, respectively.

Night-Time Operations in Transit Systems: Evaluating the Athens Metro Owl Services

Public transport operators make significant efforts toward improving the quality of operations by upgrading and maintaining infrastructure and rolling stock, training personnel, and offering better and more responsive services to passengers. Among these responsive services is the extension of service at night (night-time extension) whose goal is to serve night-time demand for passengers. This paper examines, analyzes, and evaluates the performance and quality of the Athens Metro night-time service extension for a two-month trial period. Based on ridership estimates and extensive passenger satisfaction surveys, results indicate that the night-time extension attracted a considerable number of passengers who previously used their private automobiles for the same trips and that users were highly satisfied with the service.

Drone Equipment and Configuration for Crude Oil Spill Detection in Water

Purpose: The objectives of this article was to outline the various equipment and configuration of drones which can be used to detect and support oil spill response in water. The study aimed at identify the type of sensors that can be mounted on drones for effective crude oil spill detection in water.&#x0D; Methodology: A systematic review of past articles on drones in disaster management was done. In this article, various parts of drone and configuration was tested. Sensors capable of detecting crude oil in the visible, infra-red, near infrared, laser fluoro-sensor were elaborated.&#x0D; Findings: A drone can properly be used for oil spill response operations. Appropriate sensors mounted on the drone can detect oil spill in water and can also access locations which are not readily accessible to large ships and other aerial patrol platform. The limitation of drones is the payload capability and its inability to operate well in windy weather.&#x0D; Recommendation: Since data collection with drone are faster, cheaper and easier during an oil spill response operations, it is highly recommended to mount the suitable sensor capable of detecting oil sheen even during nighttime operations.

A Comparison of Daytime and Nighttime Operating Speed on Rural Multi- Lane Highway Sections in Egypt

Traditionally, the 85th percentile of observed speeds is used to represent the operating speed associated with a specific site with certain geometric features. The presence of sunlight enhances the vision of drivers during daytime while visibility usually degrades during nighttime, especially on rural roads where no street lighting exists, and drivers would depend solely on their vehicle headlights. Visibility degradation is a safety concern which is magnified on horizontal curves. The objective of this study, therefore, is to compare operating speed in daytime and nighttime conditions on both tangent sections and horizontal curves. The analysis made use of spot speed data collected on horizontal curves of two major rural multilane highway in Egypt. Spot speed data were collected using speed guns during daytime and nighttime. The spot speed data were used to calculate the mean speed, variance of speed, and the 85th percentile speed. Analysis of Variance (ANOVA) was used to compare the speeds in daytime and nighttime. For most cases, it was shown that no significant difference existed in speed for daytime and nighttime. This was mainly attributed to the generous design features of the highway elements (e.g., large radii of horizontal curves, wide lanes, etc.). An attempt was made to develop operating speed models to see which variables impact speed during daytime. The results of operating speed models’ development were deemed inappropriate due to the lack of variability in speeds.

Eye-Tracking in Assessment of the Mental Workload of Harvester Operators.

Harvesting large quantities of timber requires the use of various technical means, including harvesters. The introduction of machine logging has greatly improved safety and reduced accident rates but has also resulted in the risk of musculoskeletal disorders and increased psychological strain. The aim of this study was to determine the level of the mental workload of harvester operators in wind-damaged stands, during daytime and nighttime clearfelling, and during late thinning using the technique of eye-tracking (analysis of saccades and pupil dilation). The highest number of saccades for both felling and processing operations was recorded during daytime and nighttime clearcutting, while the lowest number was recorded in late thinning. For both operations, the highest mean saccade duration was found in late thinning (felling 38.7 ms, processing 36.0 ms) and the lowest in nighttime cutting (felling 33.1 ms, processing 35.5 ms). The highest frequency of saccades in both operations was recorded in clearcut areas during both daytime and nighttime operations. The largest mean pupil diameters during saccades were recorded in night clearfelling plots (felling 5.57 mm, processing 5.52 mm), while the smallest were recorded in plots with windbreaks (felling 2.91 mm, processing 2.89 mm). Comparison of the number, duration, frequency, and time proportion of saccades as well as pupil diameter provided a quantifiable assessment of mental workload in clearcut, wind-damaged, and thinning stands. The indicators analyzed showed that the cutting category can significantly affect the level of mental workload and thus fatigue of harvester operators.

Performance evaluation and parametric analysis of an integrated diurnal and nocturnal cooling system driven by photovoltaic-thermal collectors with switchable film insulation

Cooling systems integrated with photovoltaic-thermal (PVT) collectors are promising for reducing building energy consumption because PVT collectors can provide photovoltaic power generation, solar thermal cooling, and nocturnal passive cooling. Glazed and unglazed PVT collectors have typically been used in previous studies, but they lead to conflicting goals for enhancing the all-day energy performance. Glazed collectors are favorable for solar thermal cooling but result in low nocturnal passive cooling capacity, while unglazed collectors exhibit the opposite behavior. In this study, PVT collectors with switchable film insulation (i.e., PVTfilm collectors) are introduced to drive an integrated diurnal and nocturnal cooling system. Such collectors can adapt to daytime and nighttime operating modes by inflating and deflating their air cushion. Annual (8760-hour) simulations were performed based on the case study of a tropical building. Three system layouts driven by different PVT collectors were compared. The effects of key optical parameters on energy performance were analyzed. The results show that the PVTfilm collectors combine satisfactory solar thermal cooling and nocturnal passive cooling performances, with an annual total energy yield that is 10% and 32% higher than those of glazed and unglazed PVT collectors, respectively. To improve the annual total electricity savings, it is advantageous to increase the film transmittance for solar radiation, decrease the film transmittance for long-wave thermal radiation and decrease the photovoltaic panel emissivity for long-wave thermal radiation. This work is relevant for PVT systems to improve the all-day energy performance and reduce building energy consumption.