Mass Airflow Research Articles

Asthma heterogeneity and severity—why is comprehensive phenotyping important?

Asthma heterogeneity and severity—why is comprehensive phenotyping important?

Nonlinear Compensators of Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems using Air Path Models for a CRDI Diesel Engine

This paper investigates the design of model-based feedforward compensators for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems using air path models for a common-rail direct injection (CRDI) diesel engine to cope with the nonlinear control problem. The model-based feedforward compensators generate set-positions of the EGR valve and the VGT vane to track the desired mass air flow (MAF) and manifold absolute pressure (MAP) with consideration of the current engine operating conditions. In the best case, the rising time to reach 90% of the MAF set-point was reduced by 69.8% compared with the look-up table based feedforward compensators.

Transient Air-to-Fuel Ratio Control of an Spark Ignited Engine Using Linear Quadratic Tracking

Modern spark ignited (SI) internal combustion engines maintain their air-to-fuel ratio (AFR) at a desired level to maximize the three-way catalyst conversion efficiency and durability. However, maintaining the engine AFR during its transient operation is quite challenging due to rapid changes of driver demand or engine throttle. Conventional transient AFR control is based upon the inverse dynamics of the engine fueling dynamics and the measured mass air flow (MAF) rate to obtain the desired AFR of the gas mixture trapped in the cylinder. This paper develops a linear quadratic (LQ) tracking controller to regulate the transient AFR based upon a control-oriented model of the engine port fuel injection (PFI) wall wetting dynamics and the air intake dynamics from the measured airflow to the manifold pressure. The LQ tracking controller is designed to optimally track the desired AFR by minimizing the error between the trapped in-cylinder air mass and the product of the desired AFR and fuel mass over a given time interval. The performance of the optimal LQ tracking controller was compared with the conventional transient fueling control based on the inverse fueling dynamics through simulations and showed improvement over the baseline conventional inverse fueling dynamics controller. To validate the control strategy on an actual engine, a 0.4 l single cylinder direct-injection (DI) engine was used. The PFI wall wetting dynamics were simulated in the engine controller after the DI injector control signal. Engine load transition tests for the simulated PFI case were conducted on an engine dynamometer, and the results showed improvement over the baseline transient fueling controller based on the inverse fueling dynamics.

Prognostic Validation of the Body Mass Index, Airflow Obstruction, Dyspnea, and Exercise Capacity (BODE) Index in Inoperable Non–Small-Cell Lung Cancer

To investigate the prognostic utility of the body mass index, severity of airflow obstruction, measures of exertional dyspnea, and exercise capacity (BODE) index in patients with inoperable non-small-cell lung cancer (NSCLC). One hundred consecutive patients with inoperable NSCLC and performance status 0 to 3 completed pulmonary function testing, the modified Medical Research Council dyspnea scale, a 6-minute walk test, and body mass index-the multidimensional 10-point BODE index. Cox proportional models were used to estimate the risk of all-cause mortality according to the BODE index with or without adjustment for traditional prognostic factors. Median follow-up was 31.5 months; 61 deaths (61%) were reported during this period. There was a significant univariate association between the BODE index score and mortality (adjusted p(trend) = 0.027). Compared with patients with a BODE index of 0, the adjusted hazard ratio for risk of death was 1.37 (95% confidence interval [CI], 0.74-2.55) for a BODE index of 1, 1.22 (95% CI, 0.45-3.25) for a BODE index of 2, and 2.44 (95% CI, 1.19-4.99) for a BODE index more than 2. The BODE index provided incremental prognostic information beyond that provided traditional markers of prognosis (adjusted p(trend) = 0.051). Every one-point increase in the BODE index, the risk of death increased by 25% (hazard ratio = 1.25; 95% CI, 1.27-4.64). The BODE index is a strong independent predictor of survival in inoperable NSCLC beyond traditional risk factors. Use of this multidimensional tool may improve risk stratification and prognostication in NSCLC.

Novel mass air flow meter for automobile industry based on thermal flow microsensor. II. Flow meter, test procedures and results

A prototype of mass air flow meter for automobile industry was developed on the basis of thermal flow microsensor. Design and manufacturing technology of the flow meter are described. Test procedure and results are presented. Developed prototype of flow meter can diagnose gas flow rates in a wide range.

Insomnia symptoms, objectively measured sleep, and disease severity in chronic obstructive pulmonary disease outpatients

BackgroundSleep disturbances are known to have a negative impact on a range of clinical outcomes in chronic obstructive pulmonary disease (COPD). We examined the associations of insomnia symptoms and objectively measured sleep parameters to a composite score for body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index (a multidimensional index of COPD severity), arterial blood gases, nocturnal respiratory disturbances, periodic limb movements (PLM), psychologic distress, pain, age, and sex. MethodsThe sample comprised 73 COPD outpatients (mean age, 63.6years; standard deviation {SD}, 7.5; range 47–85years; 41.1% women). Insomnia symptoms were measured with the Bergen Insomnia Scale (BIS) and sleep efficiency (SE), slow-wave sleep (SWS), and total sleep time (TST) were assessed with clinical polysomnography (PSG). ResultsBODE index was positively associated with composite BIS score (P=.040). Patients with more severe COPD presented more complaints of nonrestorative sleep compared to patients with less severe COPD (P=.010). In multivariate analysis, the composite BIS score was independently associated with PLM (P<.001), nocturnal respiratory disturbances (P=.001), pain (P=.031), and psychologic distress (P=.044) but not with the BODE index. Objectively measured sleep variables were not associated with any of the health-related variables. ConclusionInsomnia symptoms in COPD patients result from a wide range of health-related factors. More severe COPD may be associated with a subjective experience of nonrestorative sleep but not with objectively measured sleep variables.

Reduced level of physical activity in Japanese patients with chronic obstructive pulmonary disease

There is increasing interest in the quantification of physical activity (PA) with an accelerometer for the management of chronic obstructive pulmonary disease (COPD). However, a detailed understanding of the PA in Japanese patients with COPD is lacking. We evaluated the levels of PA in terms of intensity in Japanese patients with COPD and evaluated the factors, which could influence the PA. Forty-three outpatients with COPD and 21 age-matched healthy subjects were monitored with a triaxial accelerometer, and their PA was compared. Furthermore, the effects of pulmonary function, ADO index (age, dyspnea, and airflow obstruction) and modified BODE index (body mass index, airflow obstruction, dyspnea, and exercise capacity) on the PA were evaluated. The PA in COPD was significantly reduced at all intensities. The reduced levels of PA in COPD were 23.1% at ≥2.0 metabolic equivalents (METs), 33.0% at ≥2.5 METs, 50.9% at ≥3.0 METs, and 66.9% at ≥3.5 METs, compared with that of healthy subjects, and the reduction was significant at GOLD stage III. The values of FVC, FEV1.0, and DLCO/VA were correlated with that of the PA, but the lung volume parameters were not. The ADO and modified BODE indices were also well correlated with the PA. The reduced levels of PA in Japanese patients with COPD were objectively demonstrated in terms of intensity that could provide us a new target for the management of COPD.

Computed Tomographic Measures of Pulmonary Vascular Morphology in Smokers and Their Clinical Implications

Angiographic investigation suggests that pulmonary vascular remodeling in smokers is characterized by distal pruning of the blood vessels. Using volumetric computed tomography scans of the chest we sought to quantitatively evaluate this process and assess its clinical associations. Pulmonary vessels were automatically identified, segmented, and measured. Total blood vessel volume (TBV) and the aggregate vessel volume for vessels less than 5 mm(2) (BV5) were calculated for all lobes. The lobe-specific BV5 measures were normalized to the TBV of that lobe and the nonvascular tissue volume (BV5/T(issue)V) to calculate lobe-specific BV5/TBV and BV5/T(issue)V ratios. Densitometric measures of emphysema were obtained using a Hounsfield unit threshold of -950 (%LAA-950). Measures of chronic obstructive pulmonary disease severity included single breath measures of diffusing capacity of carbon monoxide, oxygen saturation, the 6-minute-walk distance, St George's Respiratory Questionnaire total score (SGRQ), and the body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index. The %LAA-950 was inversely related to all calculated vascular ratios. In multivariate models including age, sex, and %LAA-950, lobe-specific measurements of BV5/TBV were directly related to resting oxygen saturation and inversely associated with both the SGRQ and BODE scores. In similar multivariate adjustment lobe-specific BV5/T(issue)V ratios were inversely related to resting oxygen saturation, diffusing capacity of carbon monoxide, 6-minute-walk distance, and directly related to the SGRQ and BODE. Smoking-related chronic obstructive pulmonary disease is characterized by distal pruning of the small blood vessels (<5 mm(2)) and loss of tissue in excess of the vasculature. The magnitude of these changes predicts the clinical severity of disease.

Metabolic Disease and Participant Age Are Independent Predictors of Response to Pulmonary Rehabilitation

The study aims were (1) to determine whether baseline measures-including the Body Mass Index, Airflow Obstruction, Dyspnea, and Exercise Capacity (BODE) index; Age, Dyspnea, and Airflow Obstruction (ADO) index; physical activity; comorbidities (cardiac, metabolic, or musculoskeletal disease); and the number of hospitalizations over the previous 12 months-can predict responders in 6-minute walk distance (6MWD) following pulmonary rehabilitation (PR) and (2) to determine whether different methods in defining improvement in 6MWD affected identifying responders to PR. All participants with chronic obstructive pulmonary disease who attended PR at our institution between 2004 and 2009 were evaluated. A participant was classified as a responder with improvement in 6MWD (≥25 m or ≥2 SD of this dataset coefficient of repeatability). A total of 203 participants (mean age, 68.2 ± 8.7 years; mean predicted forced expiratory volume in 1 second, 52.5 ± 22.4%) were analyzed. One hundred twenty participants (59.1%) had a comorbidity categorized as cardiac, metabolic, or musculoskeletal disease. The binary logistic regression models showed that younger participants (P ≤ .015) and, when using the coefficient of repeatability method (≥60.9 m), participants with metabolic disease (P = .040) were the only independent predictors of response. No other measure, including participant BODE or ADO index scores, contributed to either model. Identifying responders in exercise capacity following PR remains difficult, with only age and participants with metabolic disease identified as independent predictors.

Development of a Small Scale Concentrating Parabolic trough Solar Collector for Drying Purposes

A high performance solar collector was developed to modify agricultural building environment such as dairy, poultry farm buildings and greenhouses. Moreover it should be efficiently utilized as a solar dryer for drying various agricultural products and by products. The materials used include steel sheet with high performance of reflecting light, absorber tube, and angle iron and fully insulated drying chamber. A CPTSC was a tilted at 340south (Equivalent to the latitude of Peshawar) Pakistan. A CPTSC a total reflecting surface area was 2.9 m2 respectively. The absorber tube having a surface of 0.376 m2 was fixed in front of the reflector at the distance equal to the focal length. The total volume of drying chamber was 0.3135 m3. An experiment was conducted to enhance the efficiency of the CPTSC and two air mass flow rate treatments were tested with normal and convective mass air flow rate, 0.6 kg. Min-1 and 1.72 kg. Min-1 under the average temperature of the month (January, February and March, 2012). Moreover, the process was replicated three times under the completely randomized design. The result showed that both air mass flow rate and average temperature of the month significantly effected the efficiency of a concentrating parabolic trough solar collector. The new model of a CPTSC increased the efficiency from 8 to 25 % with increase in both air mass flow rates and average temperature of the months. Therefore it is concluded that the solar collector efficiency increased with increasing air mass flow rate.

Abnormal heart rate recovery and chronotropic incompetence on exercise in chronic obstructive pulmonary disease

Chronotropic incompetence (CI; failure to reach the targeted heart rate (HR) on exercise) and a delayed HR recovery (HRR; ≤12 beats decline within the first minute after cessation) reflect autonomic dysfunction (AD) and predict adverse cardiac prognosis. As chronic obstructive pulmonary disease (COPD) is known to be associated with AD, we hypothesized that these patients may manifest these responses on exercise. The prevalence and predictors of these responses in COPD and their association with its severity have not been evaluated. Normoxemic, stable male patients with COPD (n=39) and 11 healthy controls underwent lung function testing and incremental leg ergometry. HR responses were monitored during exercise and recovery to compute the HRR and CI. Of all the patients, 33 (84.6%) had at least one of the two exercise responses as abnormal, with the majority (23, 58.9%) having both an abnormal HRR and CI. The frequency of abnormal responses increased with increasing Global Initiative for Chronic Obstructive Lung Disease stage and body mass index, airflow obstruction, dyspnoea and exercise capacity index. After adjusting for smoking history and post-bronchodilator forced expiratory volume in 1 second, only a reduced diffusion capacity for carbon monoxide predicted abnormal HRR, though weakly. We concluded that abnormal HRR and CI are common in patients with COPD. These responses are observed with increasing frequency as the severity of disease increases.

AFR-Based Fuel Ethanol Content Estimation in Flex-Fuel Engines Tolerant to MAF Sensor Drifts

Flexible fuel vehicles (FFVs) can operate on a blend of ethanol and gasoline in any volumetric concentration of up to 85% ethanol (93% in Brazil). Existing FFVs rely on ethanol sensor installed in the vehicle fueling system, or on an ethanol estimation based on air-to-fuel ratio (AFR) regulation via an exhaust gas oxygen (EGO) or λ sensor. The EGO-based ethanol detection is desirable from cost and maintenance perspectives but it is known to be prone to large errors during mass air flow sensor drifts. Ethanol content estimation can be realized by a feedback-based fuel correction of the feedforward-based fuel calculation using an exhaust gas oxygen sensor. When the fuel correction is attributed to the difference in stoichiometric air-to-fuel ratio (SAFR) between ethanol and gasoline, it can be used for ethanol estimation. When the fuel correction is attributed to a mass air flow (MAF) sensor error, it can be used for sensor drift estimation and correction. Deciding under which condition to blame (and detect) ethanol and when to switch to sensor correction burdens the calibration of FFV engine controllers. Moreover, erroneous decisions can lead to biases in ethanol estimation and in MAF sensor correction. In this paper, we present AFR-based ethanol content estimation, associated sensitivity and dynamical analysis, and a cylinder air flow estimation scheme that accounts for MAF sensor drift or bias using an intake manifold absolute pressure (MAP) sensor. The proposed fusion of the MAF, MAP, and λ sensor measurements prevents severe misestimation of ethanol content in flex fuel vehicles.

Evaluation of Noise and Air Flow on a Motorized Adaptive Valve Lift and Timing Engine

This paper explains about the evaluation of intake air flow, volumetric efficiency and noise of a motor-driven engine that used an adaptive valve lift and timing mechanism (AVLT) on one intake valve. This system is developed with an aim to produce a more powerful engine through variable valve timing and lift technique. The system made the valve lifts higher without increasing the valve lift duration. Therefore, a dynamic valve lift profile with respect to the engine speed can be achieved thus varies the input and output of an engine. As a result of applying the AVLT on a motor-driven engine, the engine noise, emission noise and the mass air flow entering the engine cylinder was increased. When AVLT is employed to a maximum lift, the mass air flow of default intake valve lift was improved within a range from 8% to 46.64% in 500 rpm to 2000 rpm speed range. Maximum lift produced engine noise within a range of 2.57% to 18.13% higher than the default lift throughout all speed. Also, maximum lift produced emission noise within a range of 2.47% to 19.19% higher than the default lift throughout all speed. The product of this research will be useful to optimise the height and timing of the valve lift and the AVLT mountings on the engine head during operation thus improves the engine performance, fuel economy, emission levels and reduced noise of a modified engine.

Experimental assessment and thermodynamic analysis of a solar desiccant cooling system

The objectives of this study were to evaluate the performance of a solar desiccant cooling system with LiCl desiccant wheel as well as to obtain useful data and experiences for practical application in Mediterranean areas with higher solar fractions. An experimental set-up was built and used to test the system performance under typical summer environmental conditions. It has been found that the required regeneration temperature of the system is low while the COP th of the system is high. Regeneration temperatures up to 65°C were recommended for each environmental condition. In addition, the effects of some important operating parameters, such as inlet temperature and humidity ratio of process and regeneration air, on system performance were also investigated in this study. Useful experiences from international standards were taken into account for the evaluation of desiccant wheels’ performance. The analysed procedure and the developed performance indicators provide useful information about the sustainability of solar desiccant cooling systems with solid desiccant wheels. This information in combination with several set of experiments was the basis for the development of nomographs, which are very helpful for the sustainability and the design analysis of solid desiccant cooling systems. This novel diagrams (nomographs) can provide information on the outlet conditions of process and regeneration air streams of a solar cooling unit with LiCl desiccant wheel and therefore the dehumidification capacity of these systems as a function of ambient conditions. The model development was followed by a sensitivity analysis performed on these predicted results. The key parameters were the thermodynamic condition of process and regeneration air streams, the thermal coefficient of performance and the mass air flow ratio of the regeneration and process streams.

Novel mass air flow meter for automobile industry based on thermal flow microsensor. I. Analytical model and microsensor

An analytical model of the thermal flow sensor has been developed. The results of analytical model application are utilized to develop a thermal flow microsensor with optimal functional characteristics. The technology to manufacture the microsensor is described. A prototype of the microsensor suitable to be used in the mass air flow meter has been designed. The basic characteristics of the microsensor are presented.

INTEGRATED MASS AIR FLOW SENSOR AND BROADBAND SILENCER

An integrated mass air flow sensor/broadband silencer assembly comprises a molded body having a plurality of walls formed therein. The molded body is over-wrapped with a layer of acoustic foam that, together with the plurality of walls, define a plurality of chambers within an interior volume of the assembly. A mass air flow sensor can be inserted into one of the chambers. The chambers are sized and spaced to provide a uniform velocity, low turbulence air flow to the sensor, and a minimally-restricted air flow to an internal combustion engine located downstream of the assembly.

Development of a Small Scale Concentrating Parabolic trough Solar Collector for Drying Purposes

A high performance solar collector was developed to modify agricultural building environment such as dairy, poultry farm buildings and greenhouses. Moreover it should be efficiently utilized as a solar dryer for drying various agricultural products and by products. The materials used include steel sheet with high performance of reflecting light, absorber tube, and angle iron and fully insulated drying chamber. A CPTSC was a tilted at 340south (Equivalent to the latitude of Peshawar) Pakistan. A CPTSC a total reflecting surface area was 2.9 m2 respectively. The absorber tube having a surface of 0.376 m2 was fixed in front of the reflector at the distance equal to the focal length. The total volume of drying chamber was 0.3135 m3. An experiment was conducted to enhance the efficiency of the CPTSC and two air mass flow rate treatments were tested with normal and convective mass air flow rate, 0.6 kg. Min-1 and 1.72 kg. Min-1 under the average temperature of the month (January, February and March, 2012). Moreover, the process was replicated three times under the completely randomized design. The result showed that both air mass flow rate and average temperature of the month significantly effected the efficiency of a concentrating parabolic trough solar collector. The new model of a CPTSC increased the efficiency from 8 to 25 % with increase in both air mass flow rates and average temperature of the months. Therefore it is concluded that the solar collector efficiency increased with increasing air mass flow rate.

Flow Microsensor of Thermal Type for Measurements of Gas Fluxes

An analytical model of the flow sensor of thermal type is developed. The results of the model application are used to develop a flow microsensor of thermal type with optimal functional characteristics. The technology of microsensor manufacturing is provided. The prototype of the microsensor suitable for use in the mass air flow meter is created. The basic characteristics of the microsensor are presented.

Multicomponent indices to predict survival in COPD: the COCOMICS study

Guidelines recommend defining chronic obstructive pulmonary disease (COPD) by airflow obstruction and other factors, but no studies have evaluated the ability of existing multicomponent indices to predict mortality up to 10 years. We conducted a patient-based pooled analysis. Survival analysis and C statistics were used to determine the best COPD index/indices according to several construct variables and by varying time-points. Individual data of 3633 patients from 11 COPD cohorts were collected, totalling the experience of 15 878 person-years. Overall, there were 1245 death events within our cohorts, with a Kaplan-Meier survival of 0.963 at 6 months, which was reduced to 0.432 at 10 years. In all patients, ADO (age, dyspnoea and forced expiratory volume in 1 s), BODE (body mass index, airflow obstruction, dyspnoea and exercise capacity) and e-BODE (BODE plus exacerbations) were the best indices to predict 6-month mortality. The ADO index was the best to predict 12-month (C statistic 0.702), 5-year (C statistic 0.695) and 10-year mortality (C statistic 0.698), and was significantly better than BODE (all p<0.05). The best indices to predict death by C statistics when adjusting by age were e-BODE, BODEx (substitution of exacerbations for exercise capacity) and BODE. No index predicts short-term survival of COPD well. All BODE modifications scored better than ADO after age adjustment. The ADO and BODE indices are overall the most valid multicomponent indices to predict time to death in all COPD patients.

Investigation of Particle and Air Flows in a Mixed-Flow Dryer

Even though the mixed-flow dryer is well established on the commercial market for the drying of grain, maize, and rice, there further potential as well as a need to optimize the dryer apparatus and to improve product quality. Unfavorable designs can cause uneven mass flow and air flow distributions, resulting in locally different drying conditions and, hence, uneven grain drying. The aim of the present article is to evaluate traditional designs of mixed-flow dryers by numerical and experimental investigation of particle and air flows and to discover design deficits. For this purpose, the dryer geometry and different air duct arrangements (horizontal and diagonal) were studied using the discrete element method (DEM) and computational fluid dynamics (CFD). Drying experiments were performed to evaluate the grain moisture and temperature distributions. With regard to particle flow, a typical core flow was detected as in silos with a retarded particle flow at the dryer walls and a fast flow region in the center of the dryer. This was caused by the wall friction effect and the half air ducts fixed at the side walls. With regard to the air flow, dead zones were discovered for the diagonal air duct arrangement. Based on the design deficits identified for the traditional geometry, a new geometry for the mixed-flow dryer that is still under development is discussed.