Mass Airflow Research Articles

Pros and cons of equipping Harmonic Acoustic Pneumatic Sources (HAPS) with quarter wave tube: analytical model versus experimental validation

Pneumatic acoustic sources enable high Sound Pressure Levels (SPL). Harmonic Acoustic Pneumatic Sources (HAPS), utilizing airflow modulation to create precise acoustic pressure fields with controlled amplitude and phase, emerge as solutions for active harmonic-noise control at high SPLs. While theoretically capable of generating pure tones, HAPS appear to be non-linear sources with significant harmonic distortion in practice. Additionally, the mass airflow consumption of this source could be a drawback in certain applications. The aims of this study is to evaluate the advantages of a Quarter-Wave Tube (QWT) located at the HAPS output. A numerical analytical linear model has been developed to compute the radiated acoustic pressure and consumed mass air flow, according to the QWT and HAPS characteristics. For the cases of HAPS equipped with various QWT, this presentation will compare experimental results with the analytical model. This aims to highlight the advantages, including increased SPL of the radiated fundamental, reduced fundamental/harmonic distortion over a wide frequency range, and decreased airflow consumption. The disadvantage is related to the space required by the QWT because its diameters must be greater than the HAPS output. Whatever, this study demonstrate that HAPS can be improved when equipped with a dedicated exhaust.

A Numerical Study on the Flow Field and Classification Performance of an Industrial-Scale Micron Air Classifier under Various Outlet Mass Airflow Rates

In this study, the gas−particle flow field in a real-size industrial-scale micron air classifier manufactured by Phenikaa Group using 3D transient simulations with the FWC-RSM–DPM (Four-Way Coupling-Reynold Stress Model-Discrete Phase Model) in ANSYS Fluent 2022 R2 and with the assistance of High-Performance Computing (HPC) systems is explored. A comparison among three coupling models is carried out, highlighting the significant influence of the interactions between solid and gas phases on the flow field. The complex two-phase flow, characterized by the formation of multiple vortices with different sizes, positions, and rotation directions, is successfully captured on the real-size model of the classifier. Additionally, analyzing the effects of the vortices on the flow field provides a comprehensive understanding of the gas–solid flow field and the classification mechanism. The effect of the outlet mass airflow rate is also investigated. The classifier’s Key Performance Indicators (KPIs: d50, K, η, ΔP) and the constrained condition of the particle size distribution curve of the final product are used to evaluate the classification efficiency. The contributions of this work are as follows: (i) a simulation analysis of a real-size industrial-scale classifier is conducted that highlights its advantages over a lab-scale one; (ii) a comparison is conducted among three coupling models, showing the advancement of four-way coupling in providing accurate results for simulations of interactions between the gas phase and particles; and (iii) the particle size distribution curve performances of a classified product under different simulation models and outlet airflow rates are addressed, from which optimal parameters can be selected in the design and operation processes to achieve the required efficiency of an air classifier.

Ultrasonography as a way of evaluating the diaphragm muscle in patients with chronic obstructive pulmonary disease.

The respiratory muscles in chronic obstructive pulmonary disease (COPD) patients have reduced strength and resistance, leading to loss of the functional ability of these muscles. Lung hyperinflation is one of the main alterations, and air trapping is the main factor limiting diaphragmatic mobility (DM) in these patients; however, its correlation with functional parameters, exercise capacity, and indicators of disease severity remains underexplored. This study aimed to assess DM in stable COPD patients and relate the findings with parameters such as the 6-minute walk test distance, forced expiratory volume in 1 second (FEV1) %predicted, residual volume (RV) %predicted, and dyspnea. An observational cohort study was conducted to measure DM using ultrasound both at rest (DMrest) and during deep inspiration (DMmax). Forty-nine patients with stable COPD were included in this study. There was a correlation between DMmax and FEV1 %predicted (R = 0.36; P = .012), RV %predicted (r = -0.42; P = .01), RV/total lung capacity (r = -0.61; P < .001), and distance reached in the 6MWT (R = 0.46; P = .001). Patients with a modified Medical Research Council score <2 exhibited greater DM than those with a score ≥2 (mean difference = 13.20 ± 4.6 mm; P = .0059). Similarly, patients with a Body Mass Index, Airflow Obstruction, Dyspnea and Exercise Capacity index ≤4 showed greater DM (61.95 mm) than those with a Body Mass Index, Airflow Obstruction, Dyspnea and Exercise Capacity index >4 (47.89 mm; mean difference = 14.05 ± 5.3 mm; 95% confidence interval = 25.09-3.01 mm). DM is correlated with bronchial obstruction (FEV1), lung hyperinflation (RV and RV/total lung capacity), exercise capacity, and dyspnea in patients with COPD, suggesting its utility as an evaluative tool in this population.

Effects of Heart Rate Variability (HRV) Biofeedback in Pulmonary Indicators and HRV Indices Among Patients with Chronic Obstructive Pulmonary Disease.

Patients with chronic obstructive pulmonary disease (COPD) exhibit reduced cardiac autonomic activity, linked to poor prognosis and exercise intolerance. While heart rate variability biofeedback (HRVB) can enhance cardiac autonomic activity in various diseases, its use in patients with COPD is limited. This study explored the impact of the HRVB on cardiac autonomic activity and pulmonary indicators in patients with COPD. Fifty-three patients with COPD were assigned to either the HRVB (n = 26) or the control group (n = 27), with both groups receiving standard medical care. The HRVB group also underwent one-hour HRVB sessions weekly for six weeks. All participants had pre- and post-test measurements, including the Six-Minute Walking Test (6MWT), lead II electrocardiogram (ECG) recording, Modified Medical Research Council Dyspnea Scale (mMRC), body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index. ECG data were analyzed for heart rate variability (HRV) as an index of cardiac autonomic activity. A two-way mixed analysis of variances demonstrated significant interaction effects of Group × Time in pulmonary indicators and HRV indices. The HRVB group exhibited significant post-test improvements, with decreased mMRC and BODE scores and increased 6MWT distance and HRV indices, compared to pre-test results. The 6MWT distance significantly increased and mMRC significantly decreased at post-test in the HRVB group compared with the control group. This study confirmed the efficacy of HRVB as an adjunct therapy in patients with COPD, showing improvements in exercise capacity, breathing difficulties, and cardiac autonomic activity.

Modeling of an Adaptive HHO Gas Controller Based on Fuzzy Logic and Polynomial Function Controls to Improve Engine Torque of Gasoline Engine

Typical hydrogen-hydrogen-oxygen gas (HHO) usage to improve gasoline engine performance refers to the fixed HHO flow rate method, providing 0.25‒0.5 liters/minute of HHO for every 1000 cc engine size. However, the arising hypothesis expresses that the fixed HHO flow rate method does not optimally improve engine torque for various loads. The research objective is to propose an adaptive HHO gas controller that manages the HHO generator to produce an appropriate HHO flow rate for engine operation by adapting to load and engine speed variations. Hence, the engine torque improvement optimally occurs for various loads. The adaptive HHO controller combines fuzzy logic and polynomial function controls involving real-time engine data, such as mass airflow (MAF), air-fuel ratio (AFR), and the commanded AFR from the engine control unit (ECU), whose values vary with load and engine speed. A system simulation based on Matlab-Simulink investigates engine performance improvement due to the controller. The results show that the adaptive HHO flow rate due to the proposed adaptive HHO controller improves engine torque during small, medium, and big-loaded engine operations, respectively, by 1.5%‒4.7%, 6.8%‒26.8%, and 21.1%‒72.8% depending on engine speed 2500 rpm‒4000 rpm) and the commanded AFR (12.6‒15.4). Conversely, under the same condition, the fixed HHO flow rate with 0.75 liters/minute HHO for a 1500 cc engine, used for comparison, improves the engine torque by 0%‒0.6%, 0.3%‒14.2%, and 9.3%‒50.1%, respectively. The data show that the adaptive HHO controller provides better improvement. Moreover, the adaptive HHO controller improves engine thermal efficiency and reduces AFR error against the commanded AFR.

Optimization of NOX emissions of a CRDI DIESEL engine using CMA-ES method

Engine calibration is the tuning of embedded parameters in the engine control unit (ECU) software to improve vehicle characteristics and meet legal requirements. Due to the stricter emission limits and rising customer expectations, current ECU software may include variables up to 30,000, which require very much time for engine calibration development. For this reason, automotive manufacturers continuously develop mathematical-based optimization methods to find optimum operating conditions for the engines. This study aimed to develop an online optimization algorithm to conduct automated dynamometer tests in the calibration development process. A modified covariance matrix adaptation (CMA) algorithm, which is an evolutionary strategy (ES) method belonging to meta-heuristic optimization, was integrated with an automation system for online calibration optimization. Some CMA method parameters such as step size and damping factor were initially revised to achieve the method to function efficiently in online engine calibration. Optimization was conducted at three different operating points of a 2-liter common rail direct injection (CRDI) diesel engine, where NOx emission mainly impacts the New European Driving Cycle (NEDC) results. The main injection timing, rail pressure, pilot injection quantity and timing, manifold pressure, and mass air flow were controlled in the optimization process. Optimization targets were determined according to the NOx-PM Pareto curve for each operating point. Covariance matrix adaptation was used to generate Pareto curves. Sixty-five measurements were taken for each operating point in the optimization process. Once optimization targets were determined, optimization occurred at each operating point. A total NOx emission reduction of 3.8% was obtained in the NEDC test, while fuel consumption and PM remained almost the same at steady-state operating points. The modified CMA-ES algorithm is expected to be an efficient method for online calibration optimization.

Prevalence and clinical characteristics of Sarcopenia in older adult patients with stable chronic obstructive pulmonary disease: a cross-sectional and follow-up study

BackgroundThe relationship between sarcopenia and chronic obstructive pulmonary disease (COPD) has been increasingly reported, and there is some overlap regarding their clinical features and pulmonary rehabilitation (PR) strategies. No Korean study has reported the actual prevalence of sarcopenia in patients with stable COPD who are recommended for pulmonary rehabilitation. This study evaluated the prevalence and clinical features of sarcopenia in older adult outpatients with stable COPD and the changes after 6 months.MethodsIn this cross-sectional and 6-month follow-up study, we recruited 63 males aged ≥ 65 diagnosed with stable COPD. Sarcopenia was diagnosed using the AWGS 2019 criteria, which included hand grip strength testing, bioelectrical impedance analysis, Short Physical Performance Battery administration, and Strength, Assistance with walking, Rising from a chair, Climbing stairs, and Falling screening tool administration. A 6-minute walk test (6 MWT) was conducted, forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), maximal inspiratory and expiratory pressures (MIP and MEP, respectively) and peak expiratory flow (PEF) were assessed, and patient-reported questionnaires were administered.ResultsAt baseline, 14 (22%) patients were diagnosed with possible sarcopenia, and eight (12.6%) were diagnosed with sarcopenia. There were significant differences in the age; body mass index; Body mass index, airflow Obstruction, Dyspnea, and Exercise index; modified Medical Research Council dyspnea scores; and International Physical Activity Questionnaire scores between the normal and sarcopenia groups. Whole-body phase angle, MIP, MEP, PEF, and 6-minute walk distance (6 MWD) also showed significant differences. Over 6 months, the proportion of patients with a reduced FEV1 increased; however, the proportion of patients with sarcopenia did not increase.ConclusionA relatively low prevalence of sarcopenia was observed in older adult outpatients with stable COPD. No significant change in the prevalence of sarcopenia was found during the 6-month follow-up period.Trial registrationThe study was registered with the Clinical Research Information Service (KCT0006720). Registration date: 30/07/2021.

Analisis Perbandingan Kinerja Alat Pengering Rumah Kaca Tipe Rotari Sistem Tertutup Dengan Sistem Semi Tertutup Terintegrasi Dengan Tungku Biomasa Menggunakan Penukar Kalor Dua Tingkat Untuk Mengeringkan Ikan Nila

The aim of this research is to compare the performance of an open system rotary type greenhouse effect dryer (APERK-TR-STP) system 1 with a closed system (APERK-TR-SST) system 2 for drying tilapia fish. In the APERK-TR- system, 1 fish is dried from an initial weight of 90.56 kg (initial water content 69.08% wet basis (bb) to a final weight of 30.33 kg (final moisture content 20% bw) at an average temperature 56.38 oC with a mass air flow rate of 0.459 kg/s takes 12 hours. Meanwhile in the APERK-TR-SST system 2 tilapia fish are dried from an initial weight of 91.49 kg (initial water content 69.40% bw) up to final weight of 19.27 kg (final moisture content 20% bw) at an average temperature of 53.98 oC with an air mass flow rate of 0.459 kg/s required 12 hours

A Vibration Analysis for the Evaluation of Fuel Rail Pressure and Mass Air Flow Sensors on a Diesel Engine: Strategies for Predictive Maintenance.

This research focuses on the analysis of vibration of a compression ignition engine (CIE), specifically examining potential failures in the Fuel Rail Pressure (FRP) and Mass Air Flow (MAF) sensors, which are critical to combustion control. In line with current trends in mechanical system condition monitoring, we are incorporating information from these sensors to monitor engine health. This research proposes a method to validate the correct functioning of these sensors by analysing vibration signals from the engine. The effectiveness of the proposal is confirmed using real data from a Common Rail Direct Injection (CRDi) engine. Simulations using a GT 508 pressure simulator mimic FRP sensor failures and an adjustable potentiometer manipulates the MAF sensor signal. Vibration data from the engine are processed in MATLAB using frequency domain techniques to investigate the vibration response. The results show that the proposal provides a basis for an efficient predictive maintenance strategy for the MEC engine. The early detection of FRP and MAF sensor problems through a vibration analysis improves engine performance and reliability, minimizing downtime and repair costs. This research contributes to the advancement of monitoring and diagnostic techniques in mechanical engines, thereby improving their efficiency and durability.

Air Equalizing Mechanism in Cooling Performance Improvement of Vertical Delta-Type Radiators

Based on the design and measured data of one actual tower, a three-dimensional numerical model for a natural draft dry cooling tower (NDDCT) was created and validated under constant heat load. This enabled the performance improvement mechanism of air equalizing on vertical delta-type radiators (VDRs) to be clarified by detailed analysis of key parameters, such as the exit water temperature, heat transfer coefficient, and mass airflow. Under the impact of typical ambient crosswind, all VDRs were retrofitted with air-side-equalizing devices. It was found that the exit water temperatures of the whole NDDCT decreased by 0.865 °C, 0.593 °C and 0.186 °C under the studied ambient crosswind speeds of 2.5 m/s, 4 m/s and 12 m/s, respectively. The performance improvement mechanism of air-side equalizing was investigated for three VDRs, which were located on the upwind, tower lateral, and downwind sides under crosswind impacts. Besides the studied VDRs, the performance of the neighboring VDRs behind them was also improved by the optimized aerodynamic field and the reduced hot wind recirculation around them. In addition, the average heat transfer coefficients of the VDRs were enhanced, which could lay the foundation for improving the cooling performance of thermodynamic devices with VDRs.

Features of calculating the temperature field in an annular porous layer under infinite heating

To date, easily recoverable oil reserves have already been extracted, so deposits with residual oil reserves or places with weak permeability are of great interest. It is known that oil becomes more viscous when the temperature decreases, which creates difficulties in its production. Therefore, to reduce the viscosity, it is necessary to heat the oil to the temperature at which it is possible to realize its production. The study proposes a mathematical model for calculating the temperature field in an annular porous layer under infinite heating in a downhole reactor for continuous heating of the bottom-hole zone of a formation containing high-viscosity oil and natural bitumen (HVO and NB).PURPOSE. To construct a heating solution for an infinitely long annular layer in a downhole reactor. To obtain a temperature profile in the cross section of the annular layer and a picture of the temperature field.METHODS. The equations of the mathematical model are based on the laws of conservation of energy and mass, their study and evaluation are carried out using analytical methods of the theory of differential equations, methods of similarity theory and dimensions, as well as numerical methods for solving boundary value problems. results. In the course of the study, the dependences of the distance at which the set air temperature in the reactor is reached at different values of mass air flow, linear heat flux density and the heat capacity of the mixture were obtained. conclusion. The conducted studies have allowed us to obtain a mathematical model for calculating the temperature field in an annular porous layer under infinite heating in an downhole reactor. The results obtained showed that with an increase in the mass flow rate and the heat capacity of the medium, the distance at which the set air temperature in the reactor is reached increases by 1.6 and 1.5 times, respectively, over the entire temperature range, and with an increase in the linear density of the heat flux, this distance decreases by 0.6 times.

Multidisciplinary diagnosis and treatment model based on a retrospective cohort study: Pulmonary function and prognosis quality of life in severe COPD.

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease worsening airflow limitation. To explore pulmonary function rehabilitation, life quality and prognosis in patients with severe COPD. Between February 2018 and August 2021, 150 patients with severe COPD cured in our hospital were arbitrarily assigned into the control group (n= 75) and study group (n= 75). The control group received routine treatment and the research group received multidisciplinary diagnosis and treatment. The body mass index, airflow obstruction, dyspnea and exercise (BODE), pulmonary function, the number of acute attacks, 6-minute walking distance (6MWD), Borg score and life quality were compared. There was no remarkable difference in BODE score before treatment (P> 0.05). During the 2- and 6-month following treatment, the BODE score of the study group was lower (P< 0.05). In the study group, FEV1 percentage of the predicted value, forced expiratory volume in one second (PPO-FEV1) and the percentage of forced expiratory volume in one second/forced vital capacity (FEV1/FVC) in the first second were higher (P< 0.05). In the study group, there were fewer acute attacks (P< 0.05). After treatment, the 6MWD of the study group following 2- and 6-month treatment was higher (P< 0.05). The Borg scores of the study group at 2- and 6-months after treatment were lower (P< 0.05). There were no remarkable differences in the score of life quality before treatment (P> 0.05), however, the symptom score, activity score, influence score and total score of the study group were lower after the treatment (P< 0.05). The application of multidisciplinary diagnosis and treatment model can promote the rehabilitation of pulmonary function of patients with severe COPD, improve their prognosis, slow down the development of the disease and enhance their life quality.

К вопросам транспортировки гептила железнодорожным транспортом

Purpose: To estimate the properties of heptyl and its effect on the human body and the environment. To provide an overview of the sphere of heptyl application and the features of its transportation by rail. To consider the structural features of the model 15-629 tank car and to perform a calculation to select the optimal crosssectional area for the inlet opening of the relief valve to enhance safety during the transportation of heptyl by the model 15-629 tank car. Methods: To calculate the inner and outer surface areas of the tank shell using the technical characteristics of the six-axis multi-unit tank-car of model 15-629. Next, we will calculate the mass air flow rate through the inlet relief valve and determine the heat transfer occurring due to the external heat dissipation from the tank shell into the surrounding environment. These data are necessary to estimate the equivalent diameter of the inlet relief valve orifice. Results: Thanks to the calculations performed, a more suitable diameter of the inlet safety valve orifice has been determined. This will ensure a safer transportation of highly toxic liquid rocket fuel components used in both Russian launch vehicles (“Kosmos”, “Cyclone”, “Proton”) and international ones (such as American “Titan” rockets, French launch vehicles of the “Ariane”, Chinese rockets of the “Long March” family, and others). Practical significance: Hydrazine-based propellants are more energy-efficient compared to hydrocarbon-based propellants, which has led to an increased usage of Unsymmetrical Dimethylhydrazine (UDMH) in recent years. Due to the rapid growth of space industry, the volume of heptyl transportation by railway has been increasing. In order to prevent technological disasters, calculations have been conducted to determine the diameter of the inlet relief valve to minimize depressurization of the tank car, regardless of temperature conditions.

Efficiency optimization of a vehicle combustion engine by the adjustment of the spark advance angle

Changing the ignition advance angle has a significant impact on the performance of a combustion engine. Optimization of ignition advance angle is a major task of adjusting engine concerning emission standards, fuel consumption, torque value, etc. The results of the research showed that the process of optimizing ignition advance curve can noticeably increase engine efficiency, as well as torque and power output from the engine, while reducing fuel consumption as a result of lower indications of the air flow mass per second from MAF sensor (mass air flow sensor). The highest impact of the ignition advanced angle modifications can be seen in the area of the highest volumetric efficiency of the tested combustion engine. Almost no impact is observed within high engine speed levels. Simultaneously increasing engine load and rotation speed increases the possibility of engine knocking, which has devastating effect on engine durability.

NUMERICAL SIMULATION OF GAS-DYNAMIC AND STRENGTH CHARACTERISTICS OF A FAN FOR THE EXPERIMENTAL TEST RIG FOR INVESTIGATION OF ICE BREAKDOWN ON ROTATING WORKING BLADES

The paper is devoted to modern experimental and computational studies analysis on the point of asymmetric destruction of ice on the surfaces of the working blades of gas-turbine engine blades. A schematic diagram of an experimental setup has been developed, which consists of the following main elements: a wind tunnel, a cold chamber, a model fan, an electric motor, and a high-speed video camera. The experimental setup makes it possible to carry out laboratory studies of the ice formation and destruction processes. The choice of the experimental test rig parameters was made to allow assessing the icing of the blades of a rotating fan, which reproduces the processes occurring on gas turbine engines. Based on the results of three-dimensional gas-dynamic and strength calculations, the design and basic geometrical parameters of the flow path and the dummy fan were determined. The dependences of compression ratio Pk and the power consumption of a model fan Wcons on the value of the mass air flow Gair for a different number of rotor blades are presented. The choice of materials for the disk hub and blades of a dummy fan which experience tensile and bending loads at high rotation speeds up to 12.000 rpm was made, that satisfies the conditions of static and dynamic strength, also the allowable safety factors were evaluated, and pressure characteristics were obtained.

Mathematical Modeling and Validation of Solar-Induced Ventilation System for Vehicle Cabin Cooling in Hot Parking Conditions

Exposure to direct sunlight raises interior temperatures in vehicle cabins, risking heat-related illnesses. Solar passive techniques mitigate this issue, especially during hot parking conditions. However, a comprehensive mathematical model encompassing both solar chimney and vehicle cabin is lacking. This study develops a novel mathematical model to predict temperature distribution and airflow rate, enhancing system performance evaluation. The system comprises a solar air collector with an adjustable arm mounted on the vehicle's roof. The model was validated theoretically and experimentally. The experimental work is conducted with the physical model with an air gap of 0.1 m, 0.77 m width, and a 1.12 m collector length under outdoor conditions. Results indicated a gradual increase in temperatures of the glass cover, air in the collector channel, absorber, and mass airflow rate with solar radiation intensity, significantly influencing system performance. The high value of R2 and the consistency of the model's results with theoretical and experimental outcomes justified the validity and accuracy of the proposed model, exhibiting a deviation percentage of less than 10%. The developed model can be utilized to study influential parameters for optimizing the proposed strategy's performance and components, yielding comparable results to experimental data. Additionally, it provides researchers and car makers with a broader perspective and a range of options for further improvement in weight, size, cost, and aerodynamic of the vehicle.

Sensor fault‐tolerant control for an internal combustion engine

SummaryThis research presents the design of a fault‐tolerant system based on a dual extended Kalman filter (DEKF) and a bank of two high‐gain observers to ensure the continuous operation of an internal combustion engine (ICE) despite total and partial faults in the mass airflow (MAF) sensor, temperature sensor, and pressure sensor. The DEKF aims to estimate the air mass flow rate () through the throttle valve. The DEKF uses the temperature and pressure measured in the intake manifold to accurately estimate the (), a failure in any of both sensors will not allow the correct functioning of the DEKF. Therefore, a bank of two high‐gain observers is proposed to estimate the pressure and temperature from only one measure. Observer 1 estimates the temperature and pressure from the pressure, and Observer 2 uses the temperature for estimating pressure and temperature. Hence, if the temperature or pressure sensors fail, the estimated temperature or pressure will replace the ill‐measure signal. The results show the effectiveness of the proposed fault‐tolerant system in the case of one sensor or multiple sensor faults.

Comprehensive assessment of double skin façades: A mathematical model for evaluating influence of KL ratio on electrical and thermal performances, and indoor conditions

The present study proposes a mathematical model to evaluate the electrical and thermal performance of a novel Double Skin Façade (DSF) system and its impact on indoor conditions. DSF system comprises opaque PV and transparent Glass panels integrated as an exterior skin. Further, the cavity between the DSF’s exterior and interior skins provides airflow that increases PV efficiency and delivers preheated air into the room for space conditioning. The mathematical model is based on energy balance equations written, considering the DSF as an integral part of the room. This system of energy balance equations is then solved analytically under quasi-steady-state conditions for developing a mathematical model in terms of DSF’s design and climatic parameters. The model is employed to investigate multiple design parameters of DSF, including KL ratio (proportion of PV façade height to total façade height), Glass façade transmissivity, PV packing factor, cavity dimensions, and airflow rate. Montreal (Canada) is considered a pilot location for the study. The results indicate that increasing the KL ratio reduces room temperature and increases electrical output. For a fixed KL ratio, the room temperature can also be modified by adjusting the transmissivity of the exterior and interior glass façade without impacting the electrical output. A 20 % increase in the interior façade’s transmissivity results in a 2.3 ˚C rise on a winter design day and a 2.6 ˚C rise on a summer design day. Additionally, the room temperature increases with an increase in the mass airflow rate up to a certain value, after which it decreases. This behavior is attributed to the interplay between the increased convective heat transfer coefficient (which tends to increase room temperature) and the reduced flow rate factor (which tends to decrease room temperature).

Poor sleep quality, COPD severity and survival according to CASIS and Pittsburgh questionnaires

Poor sleep quality is frequent among COPD patients and it has been related to worse outcomes. The objective of this study was to compare the COPD and Asthma Sleep Impact Scale (CASIS) and the generic Pittsburgh Sleep Quality Index (PSQI) questionnaires as reliable tools for evaluating sleep quality and its relationship with COPD characteristics and survival. Stable COPD patients were prospectively evaluated. Anthropometric, sociodemographic, comorbidity, lung function and treatment data were collected. All patients completed CASIS and PSQI, mMRC dyspnea severity scale, COPD Assessment Test (CAT), sleep apnoea STOP-Bang and Hospital Anxiety and Depression Scale (HADS) questionnaires. Body mass index, airflow Obstruction, Dyspnea and Exacerbations (BODEx) index was calculated. Life status was determined after a mean follow-up of 3.7 (SD 1) years. We included 200 patients, 69.5% male, mean age 65.8 (9) years. Poor sleep was detected in 100 (50%) and 84 patients (42%) according to PSQI and CASIS questionnaires, respectively, with an agreement of 63%. Poor sleep was related to female gender, more severe dyspnea and worse BODEx, HADS and CAT scores according to both questionnaires. PSQI was associated to chronic pain or inferior urinary tract symptoms and CASIS to exacerbations, shorter walked distance in the 6-min walking test and treatment with oral corticosteroids or chronic oxygen. Thirty nine (19.5%) patients died during follow-up. Mortality was not associated to PSQI nor CASIS results. Unlike PSQI, CASIS is more related to COPD severity and its results are not influenced by comorbidities with known impact on sleep quality. In our sample, poor sleep quality was not associated with increased mortality.

Long-Term Clinical Outcomes of Patients with Chronic Obstructive Pulmonary Disease with Sarcopenia.

Sarcopenia with muscle wasting and weakness is a common occurrence among patients with chronic obstructive pulmonary disease (COPD). We aimed to evaluate the clinical outcomes of sarcopenia in patients with COPD. We reviewed the electronic medical records of 71 patients with COPD between 1 January 2012, and 31 December 2018. We longitudinally analyzed clinical outcomes in patients with COPD with and without sarcopenia. Compared to the non-sarcopenia group COPD, the sarcopenia group showed a higher rate of acute exacerbation events of COPD (AE COPD, 84.6% vs. 31.0%, p = 0.001), all-cause mortality (30.8% vs. 5.2%, p = 0.022), and pneumonia occurrence per year (median [first quartile-third quartile]; 0.2 [0.0-1.6] vs. 0.0 [0.0-0.2], p = 0.025). Sarcopenia was an independent risk factor for AE COPD in Cox regression analysis (hazard ratio, 5.982; 95% confidence interval, 1.576-22.704). Hand grip strength was associated with the COPD Assessment Test (CAT) score and annual Charlson's comorbidity index score change. Total skeletal muscle mass index (SMMI) was associated with the modified medical research council dyspnea scale score, CAT score, body mass index, airflow obstruction, dyspnea, and exercise (BODE) index, and alanine transaminase. Trunk SMMI was significantly associated with AE COPD, while appendicular SMMI was associated with BODE index and annual intensive care unit admissions for AE COPD. Sarcopenia is associated with clinical prognosis, pneumonia occurrence, and the acute exacerbation of COPD requiring intensive care in patients with COPD. Therefore, it is important to carefully monitor sarcopenia development as well as recommend appropriate exercise and nutritional supplementation in patients with COPD.