Theoretical and experimental investigation of Polymer Dispersed Liquid Crystal glazing for Net-Zero energy buildings in Saudi Arabia and UK

In the last few years, energy consumption in the building sector has increased significantly because of the economic and population growth in Saudi Arabia and the United Kingdom. Governmental bodies and policymakers have invested greatly to implement measures to reduce the energy demand and carbon emissions for the building sector. Recently, a new technology of smart windows has emerged such as Polymer Dispersed Liquid Crystal Smart Glazing (PDLC). It has the potential to dynamically control the transmittance of solar radiation into a building by altering the optical and thermal properties. To evaluate the PDLC glazing for building applications, certain properties such as spectral transmission, thermal, and daylight performance need to be investigated. Therefore, this research aims to investigate PDLC glazing to characterise the thermal and daylight performance for energy efficiency for buildings in Saudi Arabia and the United Kingdom. To investigate the thermal and daylight performance of PDLC glazing, theoretical and experimental methodologies were used. In the indoor experiment, the PDLC glazing was investigated to evaluate the spectral transmission and determine the thermal properties. In the outdoor experiment, the PDLC glazing was investigated with and without a solar control film to evaluate the thermal behaviour and daylight performance under various sky conditions. Furthermore, the EnergyPlus simulation tool was used to perform building energy modelling and daylight analysis to evaluate the potential of energy saving of the PDLC glazing for an office building in Saudi Arabia (arid climate) and the United Kingdom (temperate climate). The result of the indoor investigation showed that the investigated PDLC glazing has 2.79 W/m2·K and 2.44 W/m2·K for transparent and opaques states, respectively. In addition, the outdoor evaluation revealed that the PDLC glazing effectively reduced solar heat gain when switched to the opaque state. Visual comfort was also achieved in all sky conditions (sunny, intermittent, cloudy) when a solar control film was attached to the PDLC glazing. In terms of energy savings, the EnergyPlus analysis showed that the PDLC glazing reduced cooling load by 12.7% in Riyadh and heating load by 4.9% in London

Evaluation of thermal performance for a smart switchable adaptive polymer dispersed liquid crystal (PDLC) glazing

This is the final version. Available from Elsevier via the DOI in this record. A new class of smart window technologies are gaining interest as they have the functionality to control dynamic solar radiation, shading, ventilation and energy production. They are capable of improving buildings’ energy performance by adapting to different climate conditions and bring thermal and visual comfort for occupants. Polymer-dispersed liquid crystal (PDLC) is a smart switchable window that changes its optical transmissions from translucent to transparent when an alternating electric current stimulus is introduced. The present paper discusses the results of an indoor investigation for the optical and thermal performance of a PDLC glazing system. The spectral transmittance of the investigated PDLC was evaluated for both the translucent and transparent states using UV–vis–NIR (1050) spectrophotometer. In addition, the thermal investigation was carried out in an indoor condition utilising a test cell equipped with a small scale of PDLC glazing, which was exposed to (1000, 800, 600, 400 W/m2) solar radiation for 180 min. The optical evaluation showed that the investigated PDLC glazing offered low transmission for UV (8%) and NIR (44%) in the translucent state, respectively. The result of SHGC was 0.68 and 0.63 for the transparent and translucent states, respectively, which indicates that the investigated sample could be more effective in reducing heat loads in a cold dominated climate. The U-value for the PDLC glazing was 2.79 W/m2 for the transparent and 2.44 W/m2 translucent.Engineering and Physical Sciences Research Council (EPSRC

Evaluation of thermal performance for a smart switchable adaptive polymer dispersed liquid crystal (PDLC) glazing

A new class of smart window technologies are gaining interest as they have the functionality to control dynamic solar radiation, shading, ventilation and energy production. They are capable of improving buildings’ energy performance by adapting to different climate conditions and bring thermal and visual comfort for occupants. Polymer-dispersed liquid crystal (PDLC) is a smart switchable window that changes its optical transmissions from translucent to transparent when an alternating electric current stimulus is introduced. The present paper discusses the results of an indoor investigation for the optical and thermal performance of a PDLC glazing system. The spectral transmittance of the investigated PDLC was evaluated for both the translucent and transparent states using UV–vis–NIR (1050) spectrophotometer. In addition, the thermal investigation was carried out in an indoor condition utilising a test cell equipped with a small scale of PDLC glazing, which was exposed to (1000, 800, 600, 400 W/m2) solar radiation for 180 min. The optical evaluation showed that the investigated PDLC glazing offered low transmission for UV (8%) and NIR (44%) in the translucent state, respectively. The result of SHGC was 0.68 and 0.63 for the transparent and translucent states, respectively, which indicates that the investigated sample could be more effective in reducing heat loads in a cold dominated climate. The U-value for the PDLC glazing was 2.79 W/m2 for the transparent and 2.44 W/m2 translucent

Operational Research in Education

Operational Research (OR) techniques have been applied, from the early stages of the discipline, to a wide variety of issues in education. At the government level, these include questions of what resources should be allocated to education as a whole and how these should be divided amongst the individual sectors of education and the institutions within the sectors. Another pertinent issue concerns the efficient operation of institutions, how to measure it, and whether resource allocation can be used to incentivise efficiency savings. Local governments, as well as being concerned with issues of resource allocation, may also need to make decisions regarding, for example, the creation and location of new institutions or closure of existing ones, as well as the day-to-day logistics of getting pupils to schools. Issues of concern for managers within schools and colleges include allocating the budgets, scheduling lessons and the assignment of students to courses. This survey provides an overview of the diverse problems faced by government, managers and consumers of education, and the OR techniques which have typically been applied in an effort to improve operations and provide solutions

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

A rare presentation of stroke in young age ( moyamoya disease)

A 37-year-old hypertensive housewife presented with a sudden onset of left-sided hemiplegia, hemianaesthesia, dysarthria and urinary incontinence. The condition was preceded by recurrent attacks of motor neurological deficits over a 3-year duration. She reported a history of a fall from a height at the age of 10, which was followed by a hearing deficit and a history of two caesarean sections after eclampsia. The blood pressure was 170/100 mmHg. Laboratory investigations revealed hyperglycaemia (fasting glucose 306 mg/dl) and normal kidney function tests. The computed tomography scans revealed old multiple bilateral cerebral infarcts with recent intracranial haemorrhage in the right parietal region. The inflammatory markers (ESR and CRP) and immune profile (ANA, anti-ds DNA and ANCA) were found to be normal. Cerebral angiography revealed a complete occlusion of the intracranial parts of both internal carotid arteries at their supraclinoid segments along with the proximal parts of the anterior cerebral artery and middle cerebral artery, with collaterals from the posterior circulation. Consequently, the diagnosis of moyamoya disease with the collaterals was confirmed. Antihypertensive medications and insulin were administered. Cerebral dehydration measures were undertaken with partial improvement. A superficial temporal artery-middle cerebral artery bypass operation was performed with some postoperative improvement. One month later, she suffered a new stroke with severe impairment of the level of consciousness; the computed tomography scans revealed a large recent cerebral infarct, her condition deteriorated rapidly and she died shortly thereafter

Simulation study for a switchable adaptive polymer dispersed liquid crystal smart window for two climate zones (Riyadh and London)

Polymer dispersed liquid crystal (PDLC) is an electrically switchable smart window, that can provide privacy and control solar radiation, resulting in a potential energy saving. The optical properties of the PDLC window can be altered from translucent to transparent when an alternating current power supply is applied. However, little attention has been paid to the PDLC smart window in terms of overall building energy performance. Therefore, this study aims to investigate the impact of the PDLC window on heating, cooling, and lighting loads and daylight performance, for an office building utilising energy building modelling and daylight analysis tool. The study is limited to two contrasting climate zones; an arid climate (Riyadh, Saudi Arabia) and a temperate climate (London, United Kingdom). The results showed that the PDLC window was more effective in Riyadh (arid climate) with a cooling reduction of 12.8% than London (temperate climate) with a heating reduction of 4.9%. PDLC provided excellent interior illuminance in both cities