Performance evaluation of direction-finding techniques of an acoustic source with uniform linear array

PurposeThe purpose of this paper is to show a comparative study of different direction-of-arrival (DOA) estimation techniques, namely, multiple signal classification (MUSIC) algorithm, delay-and-sum (DAS) beamforming, support vector regression (SVR), multivariate linear regression (MLR) and multivariate curvilinear regression (MCR).Design/methodology/approachThe relative delay between the microphone signals is the key attribute for the implementation of any of these techniques. The machine-learning models SVR, MLR and MCR have been trained using correlation coefficient as the feature set. However, MUSIC uses noise subspace of the covariance-matrix of the signals recorded with the microphone, whereas DAS uses the constructive and destructive interference of the microphone signals.FindingsVariations in root mean square angular error (RMSAE) values are plotted using different DOA estimation techniques at different signal-to-noise-ratio (SNR) values as 10, 14, 18, 22 and 26dB. The RMSAE curve for DAS seems to be smooth as compared to PR1, PR2 and RR but it shows a relatively higher RMSAE at higher SNR. As compared to (DAS, PR1, PR2 and RR), SVR has the lowest RMSAE such that the graph is more suppressed towards the bottom.Originality/valueDAS has a smooth curve but has higher RMSAE at higher SNR values. All the techniques show a higher RMSAE at the end-fire, i.e. angles near 90°, but comparatively, MUSIC has the lowest RMSAE near the end-fire, supporting the claim that MUSIC outperforms all other algorithms considered.

How does the embeddedness of relational behaviours in contractual relations influence inter-organisational trust in construction projects?

PurposeThis paper aims to explore the relationship between the embeddedness of relational behaviours in contractual relations and the development of inter-organisational trust between contracting parties in construction projects.Design/methodology/approachA questionnaire survey was undertaken to collect data from 310 experienced project practitioners. Hierarchical regression and curvilinear regression were mainly used to test the hypotheses.FindingsThe results validated the role of relational behaviours in boosting trust expectation, with the contractual context dampening the positive effect only slightly. However, the impact of the embedded relational behaviours on trust intention was found contingent on the equality of outcome: relational behaviours make an impact on trust intention opposite to what the equality of outcome makes; the combination of relational behaviours and the equality of outcome finally has a positive impact on trust intention. As such, the relational behaviours embedded in contractual relations would help reduce particular distrust or improve trust when the outcome is perceived equal.Research limitations/implicationsThe conclusions are derived from the Chinese cultural background and may apply to a certain geographical scope. The nonprobability sampling method also limits the generalization of some conclusions. Besides, the results may present the contractor's view better than the owner's view.Practical implicationsThis research would help the practitioners to find a balance between relational behaviours and contractual behaviours in managing inter-organisational relationship. It would also supply effective ways for contracting parties to reduce particular distrust or cultivate particular trust in construction projects.Originality/valuePrevious studies have investigated the unique impact of relational behaviours and contractual behaviours on trust. However, few of them have checked how the mixture of both kinds of behaviours influences trust. This paper contributes to this knowledge by investigating how the embeddedness of relational behaviours in contractual relations influences the trust between contracting parties.

Abstract P548: Poorer Objective Sleep is Associated With Greater Arterial Stiffness and Worsening Cardiac Diastolic Function

Aim: Few studies have examined the association between objective sleep metrics and arterial and echocardiographic (left ventricular systolic/diastolic function) markers of sub-clinical cardiovascular disease (CVD). The present study examined the association of wrist actigraphy-assessed sleep metrics with arterial stiffness, endothelial dysfunction, and left ventricular systolic/diastolic function. Methods: Fifteen young, healthy adults (21-39y; 60% women) with no history of CVD, and no current sleep-disordered breathing (WatchPat200, Itamar Medical) or sleep complaints wore Actiwatch Spectrum Plus actigraphs for eight nights (Philips Respironics, Bend OR) with accompanying sleep logs. Participants underwent fasting vascular testing including central augmented aortic pressure (AP), carotid-femoral pulse wave velocity (cfPWV) to assess arterial stiffness (SphymocorXCEL TM ), brachial artery flow mediated dilation (FMD) to assess endothelial function, and 2D echocardiography to assess left ventricular function (Terason uSmart 3300 TM ). Left ventricular function was assessed by ejection fraction (EF%), left atrial volume index (LAVI), deceleration time (DT), and mitral valve E/e’ ratio (MVE/e’) using standardized methods. Bivariate correlations investigating the association between mean total sleep time (TST), sleep efficiency % (SE), sleep-onset latency (SOL), and wake after sleep time (WASO) with cardiovascular indices were conducted. Curvilinear regression models examining quadratic relationships between TST and the cardiovascular indices were conducted. Results: On average, participants obtained 6 hrs 44 min of TST (SD=29.1), with 86.0% SE (SD=3.1), 10.6 min SOL (SD=8.5), and 37.0 min WASO (SD=11.6). cfPWV (range: 4.8-7.5), EF% (range: 60.0-72.0), LAVI (range: 15.0-26.7 mL/m 2 ), and MVE/e’ (range: 3.2-7.8) were all within normal ranges according to age and sex normative standards. Mean FMD was 9.2% (SD=4.62, range: 4.3-19.8). Correlations indicated that greater SOL was associated with greater cfPWV (r=.63, p=0.01), and AP (r=.57, p=0.03). Lower SE (r= -.70, p=0.003) and higher WASO (r=.71, p=0.003) were associated with higher MVE/e’. WASO was associated with higher DT (r=.57, p=0.04). Curvilinear regression models revealed a quadratic relationship between TST and cfPWV (F[2,11]=9.78, p=0.004) such that shorter and longer TST were associated with greater cfPWV. No sleep metrics were associated with FMD, EF%, or LAVI. Conclusions: Among normal sleeping, apparently healthy young adults, with no history of CVD, lower levels of objective sleep quality and both shorter and longer sleep duration were associated with greater arterial stiffness, whereas only lower levels of objective sleep quality were related to worsening left ventricular diastolic dysfunction. These data may have implications for CVD risk reduction in young, healthy adults.

Sex and race differences in J-Tend, J-Tpeak, and Tpeak-Tend intervals

To facilitate the precision of clinical electrocardiographic studies of J-to-Tpeak (JTp) and Tpeak-to-Tend (Tpe) intervals, the study investigated their differences between healthy females and males, and between subjects of African and Caucasian origin. In 523 healthy subjects (254 females; 236 subjects of African origin), repeated Holter recordings were used to measure QT, JT, JTp, and Tpe intervals preceded by both stable and variable heart rates. Subject-specific curvilinear regression models were used to obtain individual QTc, JTc, JTpc and Tpec intervals. Rate hysteresis, i.e., the speed with which the intervals adapted after heart rate changes, was also investigated. In all sex-race groups, Tpe intervals were not systematically heart rate dependent. Similar to QTc intervals, women had JTc, and JTpc intervals longer than males (difference 20–30 ms, p < 0.001). However, women had Tpec intervals (and rate uncorrected Tpe intervals) shorter by approximately 10 ms compared to males (p < 0.001). Subjects of African origin had significantly shorter QTc intervals than Caucasians (p < 0.001). Gradually diminishing race-difference was found for JTc, JTpc and Tpec intervals. JTc and JTpc were moderately increasing with age but Tpe/Tpec were not. Rate hysteresis of JTp was approximately 10% longer compared to that of JT (p < 0.001). In future clinical studies, Tpe interval should not be systematically corrected for heart rate and similar to the QT interval, the differences in JT, JTp and Tpe intervals should be corrected for sex. The differences in QT and JT, and JTp intervals should also be corrected for race.

Prediction and Optimization of Weld Bead Geometry

Bead geometry plays very important role in predicting the quality of weld as cooling rate of the weld depends on the height and bead width, also bead geometry determines it’s residual stresses and distortion. Weld bead geometries are outcomes of several welding parameters taken into consideration. If arc travel is high and arc power is kept low it will produce very low fusion. If electrode feed rate is kept higher width is also found to be on higher side which makes bead tto flat. Also, the parameters like current, voltage, arc travel rate, polarity affects weld bead geometry. Hence, this paper uses techniques like ANN, linear regression and curvilinear regression for predictions of weld bead geometry and their relations with different weld parameters. I. INTRODU

An advective-dispersive transport model for residential water consumption

This work applies an advective-dispersive framework to simulate utility-wide residential water consumption using the analogy of a continuum transport process. In this context, the advective-dispersive process describes how changes in real water price and seasonal weather variability influence water consumption distribution, which ultimately governs mean and total water consumption values. Water consumption response is measured using histogram data optimally fit using parametric probability density functions (PDF) that have consistent parametrization over the entire observation period. Median statistic denotes advection and prescribes location of the measurement-space PDF, while standard deviation combined with standard-score PDF denotes dispersion which provides the measurement-space PDF with scale and shape. Combining location, scale, and shape components produces a measurement-space PDF that represents the solution to advective-dispersive transport phenomena. We use a Taylor series expansion of the statistics that define the PDF along with curvilinear regression to develop constitutive relationships that define how location, scale, and shape of the PDF respond to price and weather information. This results in a fully parametrizing advective-dispersive process represented by a partial differential equation that provides a tool for anticipating the probability that households will experience water poverty or use excess amounts as price, weather, and policy considerations change through time. This approach is conducive to automation when combined with smart water metering.

Redefining ADHD Using an Adult Population: Should Inattention be Viewed as a Separate Dimension From Cognitive and Physiological Activity Level?

Objective: The purpose of this study was to reexamine the latent structure of ADHD and sluggish cognitive tempo (SCT) due to issues with construct validity. Two proposed changes to the construct include viewing hyperactivity and sluggishness (hypoactivity) as a single continuum of activity level, and viewing inattention as a separate dimension from activity level. Method: Data were collected from 1,398 adults using Amazon’s MTurk. A new scale measuring activity level was developed, and scores of Inattention were regressed onto scores of Activity Level using curvilinear regression. Results: The Activity Level scale showed acceptable levels of internal consistency, normality, and unimodality. Curvilinear regression indicates that a quadratic (curvilinear) model accurately explains a small but significant portion of the variance in levels of inattention. Conclusion: Hyperactivity and hypoactivity may be viewed as a continuum, rather than separate disorders. Inattention may have a U-shaped relationship with activity level. Linear analyses may be insufficient and inaccurate for studying ADHD.