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Breast cancer is the leading cause of cancer-related mortality in women worldwide. Despite the rapid developments in diagnostic techniques and medical sciences, pathologic diagnosis is still recognized as the gold standard for disease diagnose. Pathologic diagnosis is a time-consuming task performed for pathologists, needing profound professional knowledge and long-term accumulated diagnostic experience. Therefore, the development of automatic and precise histopathological image classification is essential for medical diagnosis. In this study, an improved VGG network was used to classify the breast cancer histopathological image from intraoperative rapid frozen sections. We adopt a transformed loss function by adding a penalty to cross-entropy in our training stage, which improved the accuracy on test data by 4.39%. Laplacian-4 was used for the enhancement of images, which contributes to the improvement of the accuracy. The accuracy of the proposed model on training data and test data reached 88.70% and 82.27%, respectively, which outperforms the original model by 9.39% of accuracy in test data. The process time was less than 0.25 s per image on average. Meanwhile, the heat maps of predictions were given to show the evidential regions in histopathological images, which could drive improvements in the accuracy, speed, and clinical value of pathological diagnoses. In addition to helping with the actual diagnosis, this technology may be a benefit to pathologists, surgeons, and patients. It might prove to be a helpful tool for pathologists in the future. [ABSTRACT FROM AUTHOR]

Over 766 million people have been infected by coronavirus disease 2019 (COVID-19) in the past 3 years, resulting in 7 million deaths. The virus is primarily transmitted through droplets or aerosols produced by coughing, sneezing, and talking. A full-scale isolation ward in Wuhan Pulmonary Hospital is modeled in this work, and water droplet diffusion is simulated using computational fluid dynamics (CFD). In an isolation ward, a local exhaust ventilation system is intended to avoid cross-infection. The existence of a local exhaust system increases turbulent movement, leading to a complete breakup of the droplet cluster and improved droplet dispersion inside the ward. When the outlet negative pressure is 4.5 Pa, the number of moving droplets in the ward decreases by approximately 30% compared to the original ward. The local exhaust system could minimize the number of droplets evaporated in the ward; however, the formation of aerosols cannot be avoided. Furthermore, 60.83%, 62.04%, 61.03%, 60.22%, 62.97%, and 61.52% of droplets produced through coughing reached patients in six different scenarios. However, the local exhaust ventilation system has no apparent influence on the control of surface contamination. In this study, several suggestions with regards to the optimization of ventilation in wards and scientific evidence are provided to ensure the air quality of hospital isolation wards. [ABSTRACT FROM AUTHOR]

Although diamond seeds are generally polished before growth, the effect of surface roughness of diamond seeds on crystal growth quality is rarely studied. In this research, three diamond seeds were prepared for researching the effect of surface roughness of diamond seed. They were made by cutting a bulk diamond and subsequently suffered partially polished, totally polished and unpolished, respectively. After a period of microwave plasma chemical vapor deposition growth, various tests were carried out on the samples. According to the microscope and step profiler, the surface roughness of diamond seed did not affect the surface roughness of long-term growth diamonds. Compared by Raman spectra, ultraviolet − visible and infra-red spectra, it indicated that a certain rough surface of diamond seed could improve the internal stress of diamond, but reduce the crystalline quality slightly. Moreover, the surface roughness had almost no impact on the optical properties of the diamond. As a result, diamond seeds with low roughness after cutting could be used for direct growth without polishing, bringing on significant economic for gem-quality diamond production. [ABSTRACT FROM AUTHOR]

Laser based directed energy deposition (L-DED) is a promising type of additive manufacturing technology. The non-destructive testing technology for the quality monitoring of L-DED processed parts is becoming more and more demanding in terms of accuracy, real-time, and ease of operation. This paper introduces a new image recognition system based on a deep convolutional neural network, which uses multiple lightweight architectures to reduce detection time. In order to eliminate the interference better, it improves the penalty function, which effectively improves the accuracy. Judging from the detection results of the data set, the accuracy of the model training reaches 94.71%, which achieves a very good image segmentation effect and solves the technical problem of in-situ monitoring of the L-DED process. This system realizes the positioning of the spatters for the first time, and at the same time, the number of spatters and area of molten pool are correlated to the laser scanning speed and the laser power. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing (AM) has the advantages of novel part morphology, new material property, and short production cycle, attracting significant attention in automobile, aerospace, and other fields. Nevertheless, the repeatability and stability of part quality are difficult to guarantee in the current metal AM process, hindering the development of metal AM technology. Vital process variables such as molten pool characteristics, spatter characteristics, surface morphology, and radiation temperature are directly related to the quality of parts. Monitoring the dynamic changes vital variables is critical. Image processing techniques such as image transformation, recognition, segmentation, and enhancement are introduced to obtain manufacturing process information through processing and analyzing rich image features. The monitoring system's processing results are usually collected in real time to help solve the repeatability and stability problems of the metal AM process. Presently, in situ and real-time monitoring methods are the most popular, and unfortunately, the literature lacks a comprehensive report. Thus, this paper thoroughly describes in situ and real-time process monitoring on the basis of image processing for metal AM. This paper reviews the in situ and real-time monitoring on the basis of traditional image processing to analyze monitoring objects, process classifications, and image processing carriers. Then, the advantages and disadvantages of in situ and real-time monitoring of metal AM based on artificial intelligence are discussed and compared. Finally, image processing algorithm generalization, quality, small samples, and image labeling problems are analyzed and discussed. A technical route for metal AM real-time feedback control is proposed by combining image processing with other technologies. [ABSTRACT FROM AUTHOR]

Wire bonding is the most popular first-level interconnection technology used in traditional electronic packaging but still needs fundamental research. This work investigated the formation and breakage mechanism of wire-bonding microwelds in typical wire-bonding material pairs by analyzing the loading force curve, total energy curve, atomic morphology, and von Mises stress. The longer the range of the high attractive force of the atoms of a material, the earlier the real contact between the wire and substrate occurs, which means the bonding is completed earlier. The higher stiffness of the material strengthens the weld and causes damage during the bonding process. [ABSTRACT FROM AUTHOR]

Plasma arc additive manufacturing (PAM) is an additive manufacturing technology that has been widely used in the past and has practical applications in many fields. The non-destructive testing methodology of PAM workpiece quality monitoring requires high level of accuracy and real-time capability. The characteristics of the melt pool and plasma arc are the keys to characterizing the dynamic manufacturing process during the powder feed PAM process, allowing for process prediction and real-time feedback control. This paper describes a new image recognition system that uses a fully convolutional network (FCN) to acquire melt pool and plasma arc morphologies simultaneously. Its image segmentation performance is compared with four conventional methods and three artificial intelligence methods. Results show that the FCN method can extract melt pool and plasma arc quickly and accurately, even in a complex manufacturing environment. The image segmentation-based FCN's accuracy is 95.1%, and the average processing time is only 84 ms, according to the results. The performance is far superior to the existing seven methods. The relationship between average captured areas (melt pool and plasma arc) and parameters of the plasma arc (current intensity and scanning speed) is then analyzed. Finally, the quality of products in terms of sample surface roughness is measured, and its relationship with the average areas of the melt pool and plasma arc is clarified. [ABSTRACT FROM AUTHOR]

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Smoking indoors generally exists in daily life, and highlighting the importance of reducing the hazard from smoke particles to non-smoking occupants is crucial. To quantitatively investigate the flow characteristics in a ventilated room, a computational fluid dynamics (CFD) method is used to assess the velocity, concentration, and inhalation levels of indoor particles using a manikin with a realistic upper respiratory tract. It realizes smoke particles' diffusion simulation from room scale to human upper respiratory tract scale. An experiment is also performed to measure PM2.5 concentrations. With the increase of a high air change rate per hour (ACH) from zero to 12.32 and 17.14, the indoor particle concentration reduces by 58.5% and 67.9%, the number of inhaled particles decreases by 22.9% and 43.8%, and the particle concentration around the occupant decreases by 10.3% and 17.5%, respectively. It shows that indoor ventilation has a drastic effect on flow characteristics, particle concentrations, and particle outcomes. ACH of 17.14 is found to significantly reduce the particle concentration around the occupant and decrease the number of smoke particles inhaled and remaining indoors. It indicates that the ventilation equipment can reduce the number of smoke particles in the room. There are still 41.3% and 31.9% particles remaining in the room when the ACH is 12.32 and 17.14, which does harm to human health. [ABSTRACT FROM AUTHOR]

Pores in the AlSi10Mg products fabricated by laser powder bed fusion (LPBF) decrease the density of components. To study the mechanism of the formation and evolution of hydrogen pores, a model based on molecular dynamics (MD) is built. The influence of initial hydrogen content, heating time, and cooling time on the porosity is analyzed. Low initial hydrogen content, long cooling time, and appropriate heating time are beneficial to decrease the porosity of LPBF-fabricated products. When the heating time is 40 ps, the cooling time is 200 ps and initial hydrogen content is 0.081%; porosity can be reduced to 3.01%. [ABSTRACT FROM AUTHOR]

The presence of particles, which can intrude into the gas bearing, is one of the most common factors in the failure of hard disk drives (HDDs). Previous works investigated particle trajectories inside air-filled drives without considering temperature effects on the distribution of particles. Actually, especially for the submicron particle, particle trajectories and trapping status are affected by the temperature gradient since the thermophoretic force cannot be ignored. In this paper, considering major heat generation components such as the spindle motor and voice coil motor (VCM), trajectories and trapping status for AlO particles inside a 2.5 inch helium-filled drive are simulated by the commercial computational fluid dynamics solver FLUENT with user-defined functions (UDFs). The trapping criterion for AlO particles is used as boundary conditions for different colliding surfaces. The results reveal that particles in the air-filled drive will more likely degrade the head-disk interface (HDI) reliability. In addition, after considering the temperature, the particle trapping rate by the disk decreases both inside the air-filled drive and the helium-filled drive. And its reduction inside the air-filled drive is larger. Moreover, small particles will more likely degrade the HDI reliability since they can follow the rotatory flow well and have more chance to collide with the disk surface, and then easily attach onto the disk surface. [ABSTRACT FROM AUTHOR]

An entrapped particle on the slider's air bearing damages the surface of the slider or the disk. The study of particle movement on and the particle adhesion mechanism onto the slider surface is critical to reduce entrapped particle-induced damage. In this paper, we proposed a dynamical model of the adhesive particle's secondary migration on the slider surface. The model predicts whether the adhered particle will remain static by the action of the aerodynamic and adhesion forces. There are three migration movement styles which are rolling, sliding and lifting away from the original adhered location. Further, particle rolling migration behaviors on the slider air bearing surface (ABS) are analyzed considering the effects of flow shear rate, particle diameter and properties. Finally, the particle migration trajectory and velocity with time on the investigated slider are presented. It was found that most particles that adhere to the slider surface remain static for the investigated slider; pure rolling motion on the slider ABS is the main migration styles. The particle with a larger diameter and air shear rate speeds up to a higher velocity, and it takes more time to speed up to the constant velocity. A particle's secondary migration motion can be observed for the particle that adheres to the slider recession region and trailing pad. Then the particle enters airflow blowing out of or rolls away from the head-disk interface. [ABSTRACT FROM AUTHOR]

Heat-assisted magnetic recording (HAMR) is a new approach, which makes the head write data easily under a low magnetic field using a laser to heat the magnetic media to reduce its coercivity, thus, it is considered to be the next generation of higher recording areal density technology. In this paper, a three-dimensional HAMR finite-element model of hard disk drive (HDD) is developed. The temperature distributions around the laser-heating area on disk surface are investigated when the HDD is filled with air and helium. The cooling effects of the disk rotation and the heat convection in head-disk interface (HDI) are also analyzed. [ABSTRACT FROM AUTHOR]

The reliability and stability of hard disk drives (HDDs) is especially important as the areal recording density increasing rapidly target to 10 Tb/in in the future. The vibration of the Head Gimbals Assembly (HGA) is inevitable by internal fluid flow during operational process. In order to improve this undesirable problem, an acoustic piezoelectric transducer (PZT) actuator which can be used to transform an electric current to an acoustic pressure field, is glued on the HDD cover inner surface to generate acoustic pressure to suppress the flow-induced off-plate vibration (FIOPV) of the HGA. In this paper, a three-dimensional finite element model of HDD is built with an acoustic PZT actuator. The FIOPV of the HGA in the air and helium-filled drives are investigated by fluid-structure interaction simulation method. The acoustic pressure induced vibration (APIV) of the HGA is analyzed by acoustics-piezoelectric-structure interaction simulation method. After that, the suppressed FIOPV after superposing the APIV and the FIOPV is obtained by following the superposition principle. [ABSTRACT FROM AUTHOR]

An entrapped particle on the slider air bearings damages the surface of the slider or the disk. The study of particle movement on and the particle adhesion mechanism onto the slider surface is critical to reduce entrapped particle-induced damage. This paper investigates the interaction between the particles and slider surface. The particle trajectories in the far-field region are calculated using the classical Runge-Kutta method. In the near-field region, where the distance between the particle and slider surface is less than the mesh size, a new model was applied to predict the particle trajectory and whether the particle will be captured or rebound from the slider surface after the collision. A rebound model was employed to calculate the particle rebound velocity and its corresponding rebound trajectory. It was found that the particle critical velocity for rebound increases as the particle size decreases. The velocity ratio decreases as the incident velocity decreases for the same particle diameter, and it is sensitive to the particle size at a low incident velocity. For the particle collides with and rebounds from the slider surface, the negative rebound velocity makes the particles bounce a small distance away from the pad surface. The force acting on the particles also changes from negative to positive values, and they possibly undergo secondary impacts on the slider surface following air flow, which further lower the particles' velocity and increases the possibility of particles adhere to the slider surface. [ABSTRACT FROM AUTHOR]

This work proposes a novel structure design of active slider with a piezoelectric actuator at the top of the slider body and a soft layer between the substrate and head elements, to efficiently control the flying height of slider. A parametric simulation was performed to obtain an optimize dimension of PZT actuator and the most efficient soft material. Then three types of slider structures were designed and investigated with considering air bearing effects to achieve large actuation efficiency. [ABSTRACT FROM AUTHOR]

In this work, we propose a novel thermal flying height control (TFC) slider, by designing a slit near the thermal heater in the slider. Design of the slit can reduce the mechanical constraints on the head elements and concentrate the heat around head elements. In turn, head elements can achieve more thermal protrusion and flying height reduction compared to the traditional TFC slider. The simulation results show that the application of the slit achieves a flying height reduction of 1.4 nm at writer and 1.7 nm at reader. Parametric study indicates that a trade off among the slit thickness ( a), the distance of the slit to ABS ( d) and thermal heater ( t) should be optimized to achieve both large flying height reduction and small difference of flying height between reader and writer. [ABSTRACT FROM AUTHOR]

In this work, we propose a novel thermal actuator by designing a thermal insulator, a thermal conductor, and their combination to the traditional thermal heater. The thermal-structure simulation coupled with air bearing simulation is used to simulate the actuation by the thermal actuator, as well as the effects on flying performance of slider being actuated. The simulation results show that an additional 0.8-1.1 nm flying height reduction can be obtained by applying the proposed thermal actuator when the flying height of TFC slider is about several nanometers. [ABSTRACT FROM AUTHOR]

The piezoelectric flying height control slider has recently been implemented in magnetic recording disk drives to reduce the flying height. This paper performs the electromechanical simulation and air-bearing simulation to investigate the effects of the shear-model deformation on the static flying attitude of PZT slider. The location of PZT sheet and air bearing surface of slider are investigated to achieve a low flying height and robust head-disk interface. The results show that a short distance of the PZT sheet to the trailing edge of the slider can help to achieve a low flying height. A small center-trailing pad of the slider can also help to achieve a low flying height, but cannot prevent the reduction in pitch angle. The depth of the center-trailing pad does not change the reduction ratio of the pitch angle when increasing the drive voltage. A big pitch angle value is needed to avoid the pitch angle falling below zero at a high drive voltage. [ABSTRACT FROM AUTHOR]

This work investigates the piezoelectric contact sensor in the thermal flying height control (TFC) slider. A finite element model is built for the thermal flying height control slider with a piezoelectric contact sensor, which is used to detect the contact between the slider and disk. A constant force is applied at the maximum thermal protrusion point of air bearing surface. The simulation results show that the ZnO sensor with shear-mode is more sensitive to contact force than that with transverse-mode. The sensitivity of contact sensor can be increased by reducing the cross-sectional area of sensor, increasing the thickness of sensor, and choosing a short distance of sensor to air bearing surface. In addition, the thermal-stress effects from TFC heater on contact sensor are significantly large and the amplitude of thermal-stress inducing output voltage is orders larger than that induced by contact force. However, by optimizing the distance of sensor to ABS, it is possible to eliminate the thermal-stress effects. Finally, the response time of thermal-stress induced electrical voltage of contact sensor is about 0.3 ms. [ABSTRACT FROM AUTHOR]

It is common for people to use N95 filtering facepiece respirators (FFRs) in daily life, especially in locations where particulate matter (PM2.5) concentration is rising. Wearing N95 FFRs is helpful to reduce inhalation of PM2.5. Although N95 FFRs block at least 95% of particles from the atmosphere, the deadspace of N95 FFRs could be a warm, wet environment that may be a perfect breeding ground for bacterial growth. This work studies the micro-climate features including the temperature distribution and water vapor condensation in the deadspace of an N95 FFR using the computational fluid dynamics (CFD) method. Then, the temperature and relative humidity inside the same type of N95 FFR are experimentally measured. There is a good agreement between the simulation and experimental results. Moreover, an experiment is conducted to study the distribution of bacteria sampled from the inner surface of an N95 FFR after donning. [ABSTRACT FROM AUTHOR]