Optimization analysis on car interior structure noise based on particle swarm optimization and RBF model

The car body’s noise transfer function reflects the acoustic characteristics between the car body structure and interior cavity, which has an important influence on the noise control in the driver’s cab. In this paper, the finite element models of the car body structure, car interior cavity and acoustic-structure coupling were built based on the car body acoustic-structure coupling of the car and the theory of noise transfer function, and car body’s noise transfer function from the excitation position to the driver’s ears was calculated. The mathematical model for optimization of the car interior structure noise was built with the root-mean-square value of the sound pressure level response at the interior reference point as the objective function, and the first-order torsional modal frequency and the overall car body mass as the constraint conditions. To reduce the optimization burdens, the design space of the variables was sampled by means of orthogonal experimental design during the optimization process, and the Radial Basis Function (RBF) models of the root-mean-square value of the sound pressure level response of the noise at the driver’s ears and first-order torsional modal frequency were built to replace the finite element models. Finally, the optimization scheme of the car body’s noise transfer function was acquired by means of Particle Swarm Optimization (PSO). The results show that the sound pressure peak within in the frequency band reduces by 2.35 dB after optimization. Meanwhile, the response curves of the noise at the driver’s ears before and after optimization were acquired by substituting the optimization scheme into the finite element model of acoustic-structure coupling. Compared with the predicted results of RBF model, the relative error of the optimized root-mean-square value of the sound pressure in the accurate model is only 0.18 %, which manifests the feasibility of the optimization scheme

Scanless optical coherence tomography for high-speed 3d biomedical microscopy

Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging modality that has found applications in a wide range of biomedical fields, such as ophthalmology diagnosis, interventional cardiology, surgical guidance, and oncology. OCT can be used to image dynamic scenes, in quantitative blood flow sensing and visualization, dynamic optical coherence elastography, and large-scale neural recording. However, the spatiotemporal resolution of OCT for dynamic imaging is limited by the approach it takes to scan the three-dimensional (3-D) space. In a typical OCT system, the incident light is focused to a point at the sample. The OCT system uses mechanical scanners (galvanometers or MEMS scanners) steer the probing beam to scan the transverse plane and acquires an A-scan at each transverse coordinate. For volumetric imaging, the OCT system scans individual voxels in a 3D Cartesian coordinate sequentially, resulting a limited imaging speed. In addition to limited spatiotemporal resolution, the use of mechanical scanners results in bulky sample arm and complex system configuration. This dissertation seeks to overcome limitations of conventional raster scanning approach for OCT data acquisition, by investigating novel methods to address OCT voxels in 3D space. Scanless OCT imaging is achieved through the use of spatial light modulator that precisely manipulates light wave to generate output with desired amplitude and phase. It is anticipated that the scanless OCT imaging technologies developed in this dissertation will introduce a significant paradigm shift in OCT scanning of 3D space and allow the observation of transient phenomena (neural activities, blood flow dynamics, etc.) with unprecedented spatiotemporal resolution. This research focuses on technology development and validation. Two approaches for scanless OCT imaging are investigated. One approach is optically computed optical coherence tomography (OC-OCT), and the other approach is Line field Fourier domain OCT (LF-FDOCT) based on spatial light modulator. OC-OCT takes a highly innovative optical computation strategy to extract signal from a specific depth directly without signal processing in a computer. The optical computation module in OC-OCT performs Fourier transform optically before data acquisition, by calculating the inner product between a Fourier basis function projected by the spatial light modulator and the Fourier domain interferometric signal. OC-OCT allows phase resolved volumetric OCT imaging without mechanical scanning, and has the capability to image an arbitrary 2D plane in a snapshot manner. LF-FDOCT illuminates the sample with a line field generated by a spatial light modulator. Interferometric signals from different transverse coordinates along the line field are dispersed by a grating and detected in parallel by the rows of a 2D camera. Cross-sectional image (Bscan) is obtained by performing Fourier transform along the rows of the camera. By scanning the line field electronically at the SLM, volumetric OCT imaging can be performed without mechanical scanning. In this dissertation, the principles of OC-OCT and LF-FDOCT technology are described. The imaging capability of OC-OCT and LF-FDOCT systems are quantitatively evaluated and demonstrated in 2D and 3D imaging experiments on a variety of samples

Abdominal Multiple Splenosis Mimicking Liver and Colon Tumors: A Case Report and Review of the Literature

Splenosis is not an uncommon disease. However, it is often misdiagnosed as malignant tumors, and then the patients underwent unnecessary operations. Unfortunately, it is very difficult to diagnose it prior to operation. We report a rare case of a 49-year-old female patient with liver and colon splenosis, misdiagnosed as liver and colon tumors, and summarize experience how to diagnose it preoperatively according to literatures. We come to conclusion that in patients who ever underwent splenectomy especially owning to trauma, and were found mass in abdomen, clinicians must consider the existence of splenosis, and take some measures, such as scintigraphy with (99m) Tc labelled heat-denatured erythrocyte rather than biopsy, to diagnose it correctly to prevent unnecessary operations

Gamified Live-streaming: Is Avatar Better than Human Being?

Live-streaming has emerged as a popular direct selling channel to foster synchronous interaction between streamers and consumers, with the avatar streamer largely underexplored. Using the data from a fashion retailer, we adopt the Generalized Synthetic Control (GSC) method to examine the effect of gamified and human live-streaming on product sales and return rate. We find that (1) the gamified live-streaming reduces product sales and the return rate simultaneously; (2) human live-streaming boosts product sales but increases the return rate, and (3) the dual-type live-streaming can increase product sales and decrease return rates. Furthermore, we proposed that the reason for the differentiated effects between gamified and human live-streaming could be driven by the impulse-buying behavior of viewers only in human live-streaming. Our findings contribute to the growing literature on the business value of AI technology and gamification in live-streaming and shed light on practical decisions made by online retailers

Influence of MgO and Hybrid Fiber on the Bonding Strength between Reactive Powder Concrete and Old Concrete

The reactive powder concrete (RPC) was used as concrete repair material in this paper. The influence of steel fiber, steel fiber + MgO, and steel fiber + MgO + polypropylene fiber (PPF) on the mechanical properties of RPC repair materials and the splitting tensile strength between RPC and old concrete was studied. Influences of steel fiber, MgO, and PPF on the splitting tensile strength were further examined by using scanning electronic microscopy (SEM) and drying shrinkage test. Results indicated that the compressive and flexural strength was improved with the increasing of steel fiber volume fraction. However, the bonding strength showed a trend from rise to decline with the increasing of steel fiber volume fraction. Although MgO caused mechanical performance degradation of RPC, it improved bonding strength between RPC and existing concrete. The influence of PPF on the mechanical properties of RPC was not obvious, whereas it further improved bonding strength by significantly reducing the early age shrinkage of RPC. Finally, the relationship of drying shrinkage and splitting tensile strength was studied, and the equation between the splitting tensile strength relative index and logarithm of drying shrinkage was obtained by function fitting

Hem-o-lok Clip Found in Common Bile Duct after Laparoscopic Cholecystectomy and Common Bile Duct Exploration: A Clinical Analysis Of 8 Cases

Currently laparoscopic cholecystectomy (LC) and common bile duct exploration (LCBDE) has become the standard surgical procedure for cholecystolithiasis and choledocholithiasis. During the operation cystic duct and vessels are usually controlled by Hem-o-lok clips. However, recently we found clips dropping into CBD in 8 patients during fiberoptic choledochoscope 2-3 months after operation. Therefore, there is risk that clip can migrate during postoperative period, which probably lead to hemorrhage and bile leakage after LC if this occurs within postoperative few days, or even cause recurrent stone in CBD. So, using of Hem-o-lok clips may be not a safe method to control vessels and cystic duct during LC. To our knowledge, this condition has not previously been reported. In our view, other more effective and safe method ligating cystic duct and gallbladder vessels, such as effective and convenient thread knotting method, should be investigated

An automatic method of above-water iceberg 3-D profiling based on autonomous surface craft (ASC) using surface images and LIDAR

This thesis reports on a novel method to build a 3-D model of the above-water portion of icebergs using surface imaging. The goal is to work towards the automation of iceberg surveys, allowing an Autonomous Surface Craft (ASC) to acquire shape and size information. After collecting data and images, the core software algorithm is made up of three parts: occluding contour finding, volume intersection, and parameter estimation. A software module is designed that could be used on the ASC to perform automatic and fast processing of above-water surface image data to determine iceberg shape and size measurement and determination. The resolution of the method is calculated using data from the iceberg database of the Program of Energy Research and Development (PERD). The method was investigated using data from field trials conducted through the summer of 2014 by surveying 8 icebergs during 3 expeditions. The results were analyzed to determine iceberg characteristics. Limitations of this method are addressed including its accuracy. Surface imaging system and LIDAR system are developed to profile the above-water iceberg in 2015

Gold Carbenes from Cycloheptatrienes: Generation and Fate

Els Carbens metàl · lics són un dels intermedis reactius fonamentals en la síntesi orgànica i han estat àmpliament utilitzats en la construcció de molècules complexes. Molts metalls de transició són coneguts per catalitzar la descomposició dels derivats de diazo com un mètode potent per generar carbens metàl · lics. Atès l'interès del nostre grup de recerca en el desenvolupament de noves transformacions catalitzades per or, trobem un nou mètode per generar or(I) carbens a través de la reacció de retro-Buchner del tautómer norcaradiene basat en l'equilibri conegut de cicloheptatrien i norcaradiens. Or(I) carbens generats per aquest mètode són espècies altament reactives i reaccionen amb molts tipus de nucleòfils per donar diversos productes que no es preparen fàcilment per altres mètodes. Aquesta tesi presenta els estudis detallats d'aquest nou mètode de generació d'or (I) carbè, incloent: ciclopropanacions, la reacció amb furans, cicloaddició (4+1) amb ciclobutens i metileneciclopropens (MCP) i insercions formals sp2 C-H.Los carbenos metálicos son uno de los intermedios más fundamentales en síntesis orgánica y se han utilizado ampliamente para preparar moléculas muy complejas. Varios metales de transición se han aplicado para la descomposición de diazocompuestos como método de generación de carbenos muy potente. Considerando el interés de nuestro grupo en el desarrollo de nuevas transformaciones catalizadas por oro, descubrimos un nuevo método para generar carbenos de oro(I) a través de una reacción retro-Buchner del tautómero norcaradieno basado en su equilibrio con el cicloheptatireno. Los carbenos de oro(I) son especies muy reactivas respeto a varios tipos de nucleófilos para formar diferentes tipos de productos que no son fáciles de preparar con otros métodos. Esta tesis presenta los estudios detallados de este nuevo método de oro(I) para la generación de carbenos, incluyendo: ciclopropanaciones, reacción con furanos, cicloadición (4+1) con ciclobutenos y metilciclopropenos (MCPs) e inserciones formales sp2 C-H.Metal carbenes are one of the fundamental reactive intermediates in organic synthesis and have been widely used in the construction of complex molecules. Many transition metals are known to catalyze the decomposition of diazo derivatives as a powerful method for the generation of metal carbenes. Considering the interest of our research group on developing new gold-catalyzed transformations, we found a new method to generate gold(I) carbenes through the retro-Buchner reaction of the norcaradiene tautomer based on the known equilibrium of cycloheptatrienes and norcaradienes. Gold(I) carbenes generated by this method are highly reactive species and react with many kinds of nucleophiles to give various products, which are not easily prepared by other methods. This thesis presents the detailed studies of this new gold(I) carbene generation method, including: cyclopropanations, reaction with furans, formal (4+1) cycloaddition with cyclobutenes and methylenecyclopropanes (MCPs), and formal sp2 C–H insertions