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To identify sound source locations by using Fourier-based Near-field Acoustical Holography (NAH), a large number of microphone measurements is generally required to span the source region and ensure a sufficiently high spatial sampling rate. As a result, such measurements are costly, a fact which has discouraged the industrial application of NAH to identify sound source locations. However, recently, compressive sensing approaches have made it feasible to identify concentrated sound sources with a limited number of microphone measurements. In the present work, sound radiation from the front face of a diesel engine was measured by using one set of measurements from a 35-channel combo-array. The locations of significant noise sources were then identified by using three compressive sensing algorithms: Wideband Acoustical Holography (WBH), l1-norm minimization, and a hybrid approach which combined WBH and l1-norm minimization. The latter approach takes advantage of the l1’ norm’s ability to locate spatially distinct sources, and WBH’s ability to suppress “ghost” sources. It was found that the hybrid algorithm can localize and visualize the major noise sources over a broad range of frequencies, even though using a relatively small number of microphones. Finally, comments are made regarding sound field reconstruction differences between the algorithms.

Background: Patients with ST-segment elevation myocardial infarction (STEMI) are often pretreated with unfractionated heparin (UFH) before a primary percutaneous coronary intervention (PPCI). UFH pretreatment is intended to lessen the thrombotic burden, but there have been conflicting study findings on its safety and efficacy. We assessed the risks and benefits of UFH pretreatment with a retrospective analysis of registry data from the STEMI network of a German metropolitan region., Methods: Data from patients with STEMI referred for PPCI from 2005 to 2020 were evaluated with an adjusted outcome analysis, including propensity score matching (PSM). The endpoints included the patency of the infarct-related artery (IRA) after PPCI, in-hospital mortality, access-site bleeding, and the peak creatine kinase (CK) level., Results: We assessed data from 4632 patients with STEMI: 4420 (95.4%) were pretreated with UFH, and 212 (4.6%) were not. After PSM of 511 vs. 187 patients, the adjusted odds ratios for the various endpoints were (pretreatment vs. no pretreatment, with 95% confidence intervals): for impaired flow of the IRA, 1.01 [0.59; 1.74]; for in-hospital mortality, 1.46 [0.88; 2.42]; and for access-site bleeding, 0.59 [0.14; 2.46]. The peak creatine kinase levels were similar in the two groups (median, 1248.0 vs. 1376.5 U/L, estimated difference -134 [-611; 341])., Conclusion: UFH pretreatment was less frequently performed in STEMI patients who had undergone cardiopulmonary resuscitation. UFH pretreatment was not associated with increased access site bleeding, nor was it found to have significantly higher efficacy with respect to the relevant endpoints. The risks and benefits of UFH pretreatment should be weighed individually in each case, as evidence from high-quality clinical trials is lacking. Data from the existing literature suggest that no pretreatment is an option to be considered, as are certain alternative antithrombotic strategies.