This paper presents diagnosis and analyses of the sound fields radiated from power transformers in 3D space under normal operational conditions. Transformers are crucial components in the power system. Good condition of a transformer is an important factor to ensure safe and reliable operations of the entire power system. Diagnosis and analyses of transformer noise are challenging because of the complexity of the acoustic environment surrounding the power grid. Previous studies have revealed that transformer noise is predominantly concentrated in the low frequency range. This low-frequency nature of transformer noise has made it extremely difficult to pinpoint the precise source locations. The present study shows that by using the Sound Viewer system, which is built on the principles of passive SODAR (Sonic Detection And Ranging) and HELS (Helmholtz Equation Least Squares) methods, we can not only pinpoint the precise locations of noise sources of a transformer, but quantify individual source strengths. Specifically, SODAR enables one to locate multiple sound sources simultaneously in 3D space over the frequency range of 20-20,000 Hz, and the HELS method enables one to reconstruct the acoustic field and acquire the optimal approximation of the acoustic pressure distribution in 3D space, time-averaged acoustic intensities, and time-averaged acoustic powers of the individual acoustic sources. The accuracy in reconstruction depends on the SNR (Signal to Noise Ratio) of the input data. The higher the SNR is, the more accurate the reconstruction becomes. Moreover, by using a spatial filter, we can eliminate the interferences of unwanted sound sources and extract the time-averaged acoustic power of a specific target. This salient feature enables us to perform a source ranking, which can be critical in designing the most cost-effective noise mitigation strategy. Results of the present study demonstrate that this technology can play a significant role in diagnosing and analyzing complex acoustic field in a non-ideal test environment, especially for transformer health monitoring and predictive maintenance in power systems.

Algorithms for an alternative integral-formulation method (AIM) are developed for predicting acoustic radiation from an arbitrary source in a free field. The main advantages of these algorithms are that the solution is always unique and the efficiency in numerical computations is very high. The input data to these algorithms consist of the normal and tangential components of the particle velocities that are specified on a hypothetical surface enclosing the source, and output data are the acoustic quantities that include the acoustic pressure, particle velocity, and acoustic intensity on and beyond the enclosure. To speed up the numerical computations, the Dijistra algorithm is adopted that searches automatically the shortest path between two neighboring nodes in carrying out line integral. Experiments in both interior and exterior regions are conducted, and the predicted acoustic pressure is checked against the benchmark value measured at the same location. The efficiency of AIM is examined and compared with that of conventional boundary element method (BEM) based Helmholtz integral formulations.

A laser-assisted see-through technology is developed to locate sound sources inside a structure and to analyze the interior sound field. Six lasers were employed to measure simultaneously the normal velocities on the exterior surface. These input data were used to locate sound sources inside a solid structure using a passive sonic detection and ranging algorithm, and then to reconstruct the interior sound field using the Helmholtz equation least squares method, and finally to observe the changes of the interior sound field over time through computer tomography. If signals are time invariant, all these can be accomplished with two lasers, one being fixed and another moving around to measure the normal surface velocity sequentially to establish transfer function with respect to the stationary laser. Once the transfer functions are established, they can be multiplied by any segment of time-domain signals measured by the fixed laser to acquire multiple normal surface velocities, as if they were measured simultaneously. This laser-assisted see-through technology has been validated experimentally and employed to observe the aerodynamically-induced sound field generated by a blower inside a projector. This development is important as it signifies a significant advancement in sound source localization, and opens the door to a class of applications presently unattainable.

Unlike a passenger sedan, a UTV (Utility Terrain Vehicle) has much more NVH (Noise, Vibration, and Harshness) problems because it is often driven on highly rugged outdoor road surfaces. Accordingly, the excitation forces from the rugged road surfaces are typically transient, unexpected, and highly intense. To minimize the NVH problems that driver and passengers may experience, the vibroacoustic characteristics of a full-size UTV must be thoroughly analyzed. This paper presents the vibration analyses of a full-size UTV. Specifically, modal analyses are applied to analyze the natural frequencies, natural modes, and damping coefficients of the steering wheel, driver floor panel, and driver seat rail. The critical resonance frequencies and resonance modes in these three areas that are critical to the driver's comfort level are determined. These results may be critically important for design modifications of a UTV to enhance the comfort level of a driver.

In the reset state, the decay reaction mechanism and bipolar switching properties of vanadium oxide thin film RRAM devices for LRS/HRS are investigated and discussed here. To discover the properties of I-V switching curves, the first order rate law behaviors of the reset state between the resistant variety properties and the reaction time were observed. To verify the decay reaction mechanism in the reset state, vanadium oxide thin films from RRAM devices were measured by different constant voltage sampling and exhibited the same decay reaction rate constant. Finally, the electrical conduction transfer mechanism and metallic filament forming model described by I-V switching properties of the RRAM devices were proven and investigated.

Part I of this paper presents analytic solutions for reconstructing the excitation forces that act on the interior surfaces of a finite solid rectangular enclosure with the fluid loading effect taken into consideration, given vibroacoustic data in the exterior region. The reason for selecting a simple structure is to facilitate the reconstruction of excitation forces. To validate these analytic solutions, we apply the reciprocity principle and demonstrate that when the resultant excitation forces are used to excite the enclosure from the inside, the same vibroacoustic responses in the exterior region in exterior region can be obtained. To illustrate this point, we consider the case in which the top panel of a rectangular box is connected to the side walls through simply-supported boundary conditions, and the rest surfaces are rigid. The top surface of this box may be excited into vibrations by any type of excitation forces from the inside with the fluid loading effect taken into consideration. Note that for arbitrarily shaped structures under arbitrary boundary conditions, numerical solutions can be obtained. Therefore, it is possible to determine the excitation forces acting inside an enclosure based on the vibroacoustic information collected in the exterior. The knowledge of the excitation forces is critically important, because it can lead to optimal mitigation strategies to mitigate undesirable noise and vibrations.

This paper presents analyses of the 3D acoustic fields generated by motorcycles at very low frequencies ([Formula: see text] Hz) at the idle speed and during sudden acceleration. Diagnosis and analyses of sound sources at low frequencies have always been a significant challenge because the directivity of low-frequency sound is very poor. To date, there are no research papers and/or reports that have demonstrated low-frequency sources localization and radiation patterns of any kind at high spatial resolution in 3D space. This study shows that by using sound viewer technologies, which include the passive sonic detection and ranging (SODAR), the Helmholtz equation least squares (HELS) method, advanced signal processing, denoising, etc., the locations of sound sources and visualization of the sound fields can be determined with high spatial resolution, even at frequencies below 150 Hz. In particular, the HELS method allows for reconstructing all the acoustic quantities, including the acoustic pressure, time-averaged acoustic intensity, time-averaged acoustic power on the source surfaces and in 3D space. The hardware needed consists of a 3D array with six free-field precision microphones with pre-amplifiers, a miniature wide-angle camera, an eight-channel digital signal processor and a laptop computer.

Micro Electro mechanical systems (MEMS) sensor is fabricated for testing low concentration gas sensing of sulphur dioxide (SO 2 ) with sensing layers of single layer tin oxide (SnO 2 ) and double layered heterojunction structure of nickel oxide and tin oxide (NiO/SnO 2 ). NiO and SnO 2 structures are deposited with RF sputtering and the elemental composition were identified with structural properties such as X-ray diffraction (XRD), Scanning electron microscope (SEM) and Energy Dispersive X-ray Analysis (EDX) analysis. Sensing results proved that NiO/SnO 2 double layered sensor had better sensing characteristics than single layered SnO 2 sensor due to the formation of p-n junctions. At 400 ppb of SO 2 gas concentration, NiO/SnO 2 sensor has maximum sensing response of 20% is recorded and at 2000 ppb, 30% sensing response is recoded. The optimal temperature of the sensor is 250 °C (∼63 mW). Selectivity of the sensor is tested with 5 different gases such as VOC, pyruvate, CO, NH 3 , SO 2 and the sensor has high and better response with SO 2 gas.

Part II of this study presents numerical simulations of reconstructing the excitation forces acting on the interior surface of an enclosure, based on the vibroacoustic information collected in the exterior region. Various types of excitation forces such as distributed, line, and point forces are considered. Moreover, fluid loading inside the enclosure is considered in the numerical simulations. Analytical proofs show that fluid loading has no impact on excitation forces, but has significant impacts on structural vibrations. This is especially true when the density of fluid medium inside an enclosure is high. Results demonstrate that when excitation forces are continuous, the accuracy in reconstruction may be very high. When excitation forces contain abrupt changes or discontinuities, for example, line and point force, the accuracy in reconstruction may be significantly reduced. This is because many expansion terms are required to properly describe the discontinuities of excitations. On the other hand, discretization grids are fixed a priori. When fixed discretization grids are used together with an increasing number of expansion terms, aliasing may occur that may completely distort the reconstructed excitation forces.

This paper presents the experimental validations of reconstructing the characteristics of the excitation forces that act inside a vibrating structure, which includes the location, type, amplitude, and spectrum, based on a single set of measurements of the normal surface velocity on the exterior surface by using the modified Helmholtz Equation Least Squares (HELS) method, as if one could see through this solid structure. Phase I of this paper shows the reconstruction of the vibroacoustic responses in the exterior region of the structure, including the field acoustic pressure, the surface acoustic pressure, the normal surface velocity or Operational Deflection Shape (ODS), the normal component of the time-averaged acoustic intensity, and the time-averaged acoustic power. Phase II of this paper illustrates the reconstruction of the excitation forces with the fluid-loading effects taken into consideration, based on the vibroacoustic responses reconstructed in the exterior region. The significance of the study, namely, the interrelationships among the excitation force, structural vibration, and acoustic radiation is discussed. The knowledge thus acquired may be important for engineers to analyze various complex noise and vibration issues in practice and to come up with the most cost-effective noise and vibration mitigation strategies.

A modified Helmholtz equation least-square (HELS) method is developed to reconstruct vibroacoustic quantities on an arbitrarily shaped vibrating structure. Unlike the traditional nearfield acoustical holography that relies on the acoustic pressures collected on a hologram surface at a short stand-off distance to a target structure, this modified HELS method takes the partial normal surface velocities and partial acoustic pressures as the input data. The advantages of this approach include but not limited to: (1) The normal surface velocities that represent the nearfield effects are collected directly, which lead to a more accurate reconstruction of the normal surface velocity distribution; (2) The field acoustic pressures are also measured, which leads to a more accurate reconstruction of the acoustic pressure on the source surface as well as in the field; and (3) There is no need to measure the normal surface velocities over the entire surface, which makes this approach quite appealing in practice because most vibrating structures do not allow for measuring the normal surface velocities over the entire source surface as there are always obstacles or constrains around a target structure. Needless to say, regularization is necessary in reconstruction process since all inverse problems are mathematically ill-posed. To validate this approach, both numerical simulations and experimental results are presented. An optimal reconstruction scheme is developed via numerical simulations to achieve the most cost-effective reconstruction results for practical applications.

This paper presents a methodology that enables one to trace back the forced-vibroacoustic components (F-VAC) that are responsible for acoustic radiation from an arbitrarily shaped structure. This methodology relies on a modified Helmholtz equation least-square (HELS) method that takes partial normal surface velocities obtained by using a laser vibrometer and partial acoustic pressures measured using a small array of microphones as input to reconstruct the distributions of the normal surface velocity and acoustic pressure over the entire source surface. Next, the normal component of the time-averaged acoustic intensity distribution is reconstructed and linked to the field acoustic pressure. Finally, the singular value decomposition (SVD) technique is used to reveal the most critical components of the structural vibrations that are responsible for acoustic radiation. The advantages of using partial normal surface velocities and acoustic pressures as input data are that: (1) it enables one to acquire the rich near-field information embedded in the normal surface velocities; (2) it is a noncontact and noninvasive measurement approach using a laser vibrometer or scanning laser and a small microphone array at a remote location; (3) it enables one to obtain a comprehensive picture of the vibroacoustic fields that traditional near-field acoustic holography (NAH) cannot offer; (4) it allows for correlating the near-field effects to the far-field acoustic pressures and revealing the root causes of structure-borne sound radiation; (5) it provides an insight into developing the most cost-effective noise reduction measures; and (6) it is suited for engineering applications since in practice there are always areas that are inaccessible for measurements. Finally, it is emphasized that although sound may be produced by structural vibrations, not all structural vibrations may produce sound. Therefore, all one needs to do is to suppress the most critical components of structural vibrations that can emit sound. Experimental validations of using F-VAC analyses to reduce sound radiation from an arbitrarily shaped structure are demonstrated.

This paper presents a new technology that enables one to locate multiple sound sources with very a large dynamic range simultaneously, including very low frequency and negative signal-to-noise ration sound sources in a non-ideal environment, where there are random background noise and unknown interfering signals. In particular, spatial resolution of source localization is frequency independent. In other words, spatial resolution remains very high at very low as well as at very high frequencies. The underlying principle of this new technology is a hybrid methodology that includes a passive SODAR (nic etection nd anging), advanced signal processing and least-squares minimization. Using this technology, engineers will be able to visualize sound sources in both real time and post processing in an adversary test environment. Live videos of sound sources localization inside a crowd machine shop are shown, where there are unknown background noise, unspecified sound reflections and reverberation, and interfering signals.

Targeting metabolic reprogramming is an emerging strategy in cancer therapy. However, clinical attempts to target metabolic reprogramming have been proved to be challenging, with metabolic heterogeneity of cancer being one of many reasons that causes treatment failure. Here, we stratified non-small cell lung cancer (NSCLC) cells, mainly lung adenocarcinoma, based on their metabolic phenotypes and demonstrated that the aerobic glycolysis-preference NSCLC cell subtype was resistant to the OXPHOS-targeting inhibitors. We identified that monocarboxylate transporter 4 (MCT4), a lactate transporter, was highly expressed in the aerobic glycolysis-preference subtype with function supporting the proliferation of these cells. Glucose could induce the expression of MCT4 in these cells through a ΔNp63α and Sp1-dependent pathway. Next, we showed that knockdown of MCT4 increased intracellular lactate concentration and induced a reactive oxygen species (ROS)-dependent cellular apoptosis in the aerobic glycolysis-preference NSCLC cell subtype. By scanning a panel of monoclonal antibodies with MCT4 neutralizing activity, we further identified a MCT4 immunoglobulin M (IgM) monoclonal antibody showing capable anti-proliferation efficacy on the aerobic glycolysis-preference NSCLC cell subtype. Our findings indicate that the metabolic heterogeneity is a critical factor for NSCLC therapy and manipulating the expression or function of MCT4 can be an effective strategy in targeting the aerobic glycolysis-preference NSCLC cell subtype.

This paper presents a comprehensive study to determine the structural damping and vibroacoustic responses of an arbitrarily shaped planar structure subject to non-contact acoustic excitations under free boundary conditions using a modified HELS (Helmholtz equation least squares) method. The input data consist of the normal surface velocities measured by a laser vibrometer at a discrete number of points on the source surface, and the acoustic pressures measured by a small array of microphones in the field. The normal surface velocity distribution over the entire surface of the plate is then reconstructed by the HELS method and compared to benchmark data. Similarly, the reconstructed acoustic power level spectra are compared to those measured by the array of microphones. The reconstructed vibroacoustic quantities using the modified HELS method are interrogated, and the method's accuracy evaluated. Specifically, a limited number of normal velocity data points on the surface of the target structure are taken as input to the HELS formulations. The reconstructed velocity distributions on the entire surface of the structure with much higher density even for areas of the target structure with little or no input data were compared to the benchmark results. It is worth noticing that no other vibroacoustic technologies are available that allow for complete reconstruction of the normal surface velocity distributions based on limited input data. The dimensionless damping ratio of the structure is also determined. Results indicate that the dimensionless damping ratio for metals, for instance steel, is frequency dependent rather than a constant. Moreover, the empirical formulation developed in this study enables one to get the dimensionless damping ratios continuously over the frequency range from 0 to 10,00 0 Hz. (C) 2020 Elsevier Ltd. All rights reserved.

Background The immune checkpoint blockade (ICB) targeting programmed cell death-1 (PD-1) and its ligand (PD-L1) has been proved beneficial for numerous types of cancers, including non-small-cell lung cancer (NSCLC). However, a significant number of patients with NSCLC still fail to respond to ICB due to unfavorable tumor microenvironment. To improve the efficacy, the immune-chemotherapy combination with pemetrexed, cis/carboplatin and pembrolizumab (anti-PD-1) has been recently approved as first-line treatment in advanced NSCLCs. While chemotherapeutic agents exert beneficial effects, the underlying antitumor mechanism(s) remains unclear.Methods Pemetrexed, cisplatin and other chemotherapeutic agents were tested for the potential to induce PD-L1 expression in NSCLC cells by immunoblotting and flow cytometry. The ability to prime the tumor immune microenvironment was then determined by NSCLC/T cell coculture systems and syngeneic mouse models. Subpopulations of NSCLC cells responding differently to pemetrexed were selected and subjected to RNA-sequencing analysis. The key signaling pathways were identified and validated in vitro and in vivo.Results Pemetrexed induced the transcriptional activation of PD-L1 (encoded by CD274) by inactivating thymidylate synthase (TS) in NSCLC cells and, in turn, activating T-lymphocytes when combined with the anti-PD-1/PD-L1 therapy. Nuclear factor κB (NF-κB) signaling was activated by intracellular reactive oxygen species (ROSs) that were elevated by pemetrexed-mediated TS inactivation. The TS−ROS−NF-κB regulatory axis actively involves in pemetrexed-induced PD-L1 upregulation, whereas when pemetrexed fails to induce PD-L1 expression in NSCLC cells, NF-κB signaling is unregulated. In syngeneic mouse models, the combinatory treatment of pemetrexed with anti-PD-L1 antibody created a more favorable tumor microenvironment for the inhibition of tumor growth.Conclusions Our findings reveal novel mechanisms showing that pemetrexed upregulates PD-L1 expression and primes a favorable microenvironment for ICB, which provides a mechanistic basis for the combinatory chemoimmunotherapy in NSCLC treatment.

This paper presents a new method known as laser-assisted, modified Helmholtz Equation Least Squares method-based reconstruction to determine vibro-acoustic quantities of an arbitrarily shaped vibrating structure subject to a noncontact acoustic excitation. Unlike the traditional near-field acoustical holography (NAH) that relies on the acoustic pressures measured in the near-field, this new methodology enables one to collect the input data at a remote distance by using a laser vibrometer, making measurement setup much easier than all previous NAH approaches. Most importantly, by measuring the normal components of the surface velocities at the accessible areas, one can acquire near-field information of a vibrating structure directly, rather than indirectly through reconstruction based on the acoustic pressures measured in the near field. To ensure the accuracy in reconstruction of all the vibro-acoustic characteristics of a structure, the acoustic pressures at a few points in space are also measured. By combining these partial input data, one can acquire a complete picture of the vibro-acoustic field of an arbitrarily shaped vibrating structure, which includes operation deflection shapes, distributions of the acoustic pressures and the normal component of the acoustic intensities on a source surface, and the time-averaged acoustic power of the structure. When the input power is specified, one may determine the frequency response functions, the natural modes, the structural damping ratios of the structure, sound transmission loss, sound transmission path, etc. Examples of using this technology to acquire an in-depth understanding of the vibro-acoustic characteristics of an automobile front dash panel are presented.