Desalination of seawater and brackish water is becoming an increasingly important means to address the scarcity of fresh water resources in the world. Decreasing the energy requirements and ...infrastructure costs of existing desalination technologies remains a challenge. By enabling the manipulation of matter and control of transport at nanometer length scales, the emergence of nanotechnology offers new opportunities to advance water desalination technologies. This review focuses on nanostructured materials that are directly involved in the separation of water from salt as opposed to mitigating issues such as fouling. We discuss separation mechanisms and novel transport phenomena in materials including zeolites, carbon nanotubes, and graphene with potential applications to reverse osmosis, capacitive deionization, and multi-stage flash, among others. Such nanostructured materials can potentially enable the development of next-generation desalination systems with increased efficiency and capacity.
3D LiDARs and 2D cameras are increasingly being used alongside each other in sensor rigs for perception tasks. Before these sensors can be used to gather meaningful data, however, their extrinsics ...(and intrinsics) need to be accurately calibrated, as the performance of the sensor rig is extremely sensitive to these calibration parameters. A vast majority of existing calibration techniques require significant amounts of data and/or calibration targets and human effort, severely impacting their applicability in large-scale production systems. We address this gap with CalibNet: a geometrically supervised deep network capable of automatically estimating the 6-DoF rigid body transformation between a 3D LiDAR and a 2D camera in real-time. CalibNet alleviates the need for calibration targets, thereby resulting in significant savings in calibration efforts. During training, the network only takes as input a LiDAR point cloud, the corresponding monocular image, and the camera calibration matrix K. At train time, we do not impose direct supervision (i.e., we do not directly regress to the calibration parameters, for example). Instead, we train the network to predict calibration parameters that maximize the geometric and photometric consistency of the input images and point clouds. CalibNet learns to iteratively solve the underlying geometric problem and accurately predicts extrinsic calibration parameters for a wide range of mis-calibrations, without requiring retraining or domain adaptation. The project page is hosted at https://epiception.github.io/CalibNet
Multiple reports have described myopericarditis following mRNA COVID-19 vaccination. However, data on the persistence of subclinical myocardial injury assessed by left ventricular (LV) longitudinal ...strain (LVLS) is limited.
Our aim was to assess LV function longitudinally in our cohort of COVID-19 vaccine-related myopericarditis using ejection fraction (EF), fractional shortening (FS), LVLS, and diastolic parameters.
Retrospective, single-center review of demographic, laboratory, and management data was performed on 20 patients meeting diagnostic criteria for myopericarditis after mRNA COVID-19 vaccination. Echocardiographic images were obtained on initial presentation (time 0), at a median of 12 days (7.5, 18.5; time 1), and at a median of 44 days (29.5, 83.5; time 2). FS was calculated by M-mode, EF by 5/6 area-length methods, LVLS by utilization of TOMTEC software, and diastolic function by tissue Doppler. All parameters were compared across pairs of these time points using Wilcoxon signed-rank test.
Our cohort consisted predominantly of adolescent males (85%) with mild presentation of myopericarditis. The median EF was 61.6% (54.6, 68.0), 63.8% (60.7, 68.3), 61.4% (60.1, 64.6) at times 0, 1, and 2, respectively. Upon initial presentation, 47% of our cohort had LVLS < -18%. The median LVLS was -18.6% (-16.9, -21.0) at time 0, -21.2% at time 1 (-19.4, -23.5) (p = 0.004) and -20.8% (-18.7, -21.7) at time 2 (p = 0.004, as compared to time 0).
Though many of our patients had abnormal strain during acute illness, LVLS improved longitudinally, indicating myocardial recovery. LVLS can be used as marker of subclinical myocardial injury and risk stratification in this population.
NiTiNOL (Nickel-Titanium) shape memory alloys (SMAs) are ideal replacements for titanium alloys used in bio-medical applications because of their superior properties like shape memory and super ...elasticity. The machining of NiTiNOL alloy is challenging, as it is a difficult to cut material. Hence, in the current research the experimental studies on machinability aspects of medical grade NiTiNOL SMA during wire electric discharge machining (WEDM) using zinc coated brass wire as electrode material have been carried out. Pulse time (T
), pause time (T
), wire feed (WF), and servo voltage (SV) are chosen as varying input process variables and the effects of their combinational values on output responses such as surface roughness (SR), material removal rate (MRR), and tool wear rate (TWR) are studied through response surface methodology (RSM) based developed models. Modified differential evolution (MDE) optimization technique has been developed and the convergence curve of the same has been compared with the results of differential evolution (DE) technique. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrography (EDS) analysis are carried out to study the surface morphology of the machined alloy. SV is found to be more influential process parameter for achieving better MRR with minimal SR and TWR, followed by T
, T
, and WF. The WF has good impact on reduced SR and TWR responses and found to be least significant in maximizing MRR.
Multilayer MEMS and microfluidic designs using diverse materials demand separate fabrication of device components followed by assembly to make the final device. Structural and moving components, ...labile bio-molecules, fluids and temperature-sensitive materials place special restrictions on the bonding processes that can be used for assembly of MEMS devices. We describe a room temperature "stamp and stick (SAS)" transfer bonding technique for silicon, glass and nitride surfaces using a UV curable adhesive. Alternatively, poly(dimethylsiloxane) (PDMS) can also be used as the adhesive; this is particularly useful for bonding PDMS devices. A thin layer of adhesive is first spun on a flat wafer. This adhesive layer is then selectively transferred to the device chip from the wafer using a stamping process. The device chip can then be aligned and bonded to other chips/wafers. This bonding process is conformal and works even on surfaces with uneven topography. This aspect is especially relevant to microfluidics, where good sealing can be difficult to obtain with channels on uneven surfaces. Burst pressure tests suggest that wafer bonds using the UV curable adhesive could withstand pressures of 700 kPa (7 atmospheres); those with PDMS could withstand 200 to 700 kPa (2-7 atmospheres) depending on the geometry and configuration of the device.
The aim of this study is to present the methodology of Taguchi optimization technique for minimizing the delamination at the entrance of holes in high speed drilling of carbon fiber-reinforced ...plastics (CFRPs). The drilling process parameters evaluated are spindle speed, feed, and point angle. The experiments were performed as per Taguchi’s L27 orthogonal array using cemented carbide (K20) twist drills. The defects observed at the entrance of drilled holes of CFRP plates were measured and the delamination factor was computed for each trial of the orthogonal array. The analysis of means (ANOM) and analysis of variance (ANOVA) were employed to determine the optimal process parameter levels and to analyze the effect of parameters on delamination factor. The confirmation tests with the optimal levels of parameters were carried out to illustrate the effectiveness of Taguchi design. The optimization results indicate that point angle is the most significant factor followed by feed and spindle speed. The results also highlight the importance of employing the higher speeds to minimize the delamination defects.
In this paper, the effects of process parameters on delamination during high-speed drilling of carbon fiber reinforced plastic (CFRP) composite are presented. The damage caused at the entrance of the ...drilled hole is characterized by delamination factor, which is evaluated by considering cutting speed, feed rate and point angle as affecting process parameters. The drilling experiments using cemented carbide (K20) twist drills were performed based on full factorial design of experiments with three levels defined for each of the process parameters. The computed values of delamination factor are empirically related to process parameters by developing a second order non-linear regression model based on response surface methodology (RSM). The effects of cutting speed, feed rate and point angle on delamination factor were analyzed using the models by generating response surface plots. The investigations reveal that the delamination tendency decrease with increase in cutting speed. The study also suggests low values of feed rate and point angle combination for reducing the damage. The details of model development and model adequacy test by analysis of variance (ANOVA) are presented in this paper.
Hard turning with ceramic cutting tool has several benefits over grinding process such as elimination of coolant, reduced processing costs, improved material properties, reduced power consumption and ...increased productivity. Despite its significant advantages, hard turning can not replace all grinding due to lack of data concerning surface quality and tool wear and hence there is a need to study the machinability characteristics in high precision and high-hardened components. An attempt has been made in this paper to analyze the effects of depth of cut and machining time on machinability aspects such as machining force, power, specific cutting force, surface roughness and tool wear using second order mathematical models during turning of high chromium AISI D2 cold work tool steel with CC650, CC650WG and GC6050WH ceramic inserts. The experiments were planned as per full factorial design (FFD). From the parametric analysis, it is revealed that, the CC650WG wiper insert performs better with reference to surface roughness and tool wear, while the CC650 conventional insert is useful in reducing the machining force, power and specific cutting force.
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