Optimal parameters of dynamic vibration absorber for linear damped rotary systems subjected to harmonic excitation

Dynamic vibration absorber (DVA) is a simple and effective device for vibration absorption used in many practical applications. Determination of suitable parameters for DVA is of significant importance to achieve high vibration reduction effectiveness. This paper presents a method to find the optimal parameters of a DVA attached to a linear damped rotary system excited by harmonic torque. To this end, a closed-form formula for the optimum tuning parameter is derived using the fixed-point theory based on an assumption that the damped rotary systems are lightly or moderately damped. The optimal damping ratio of DVA is found by solving a set of non-linear equations established by the Chebyshev's min-max criterion. The performance of the proposed optimal DVA is compared with that obtained by existing optimal solution in literature. It is shown that the proposed optimal parameters allow to obtain superior vibration suppression compared to existing optimal formula. Extended simulations are carried out to examine the performance of the optimally designed DVA and the sensitivity of the optimum parameters. The simulation results show that the improvement of the vibration performance on damped rotary system can be as much as 90% by using DVA

Ectopic Pregnancy Located at Pelvic Wall and Liver: Two Uncommon Case Reports From Vietnam and Mini-Review Literature

INTRODUCTION AND IMPORTANCE: Abdominal ectopic pregnancy (AEP) located at hepatic region and pelvic-wall ectopic pregnancy (EP) are rare entities, that provoking a potentially life-threatening condition. Due to insufficient data, a proper management of non-specific types remains a challenge for all gynecologists worldwide. CASE PRESENTATION: Two child-bearing age women were hospitalized due to delayed menstruation and a urine pregnancy test was positive without a determination of intrauterine pregnancy. The first EP case was located at the pelvic wall which identified incidentally during laparoscopy for a presumed tubal ectopic pregnancy on ultrasonography throughout. The second EP case was found at the hepatic region due to intermittent pain rising from the right upper quadrant region and serial ultrasonic findings. In our management, both cases were successfully assessed by laparoscopy and laparotomy without requiring further intervention, respectively. CLINICAL DISCUSSION: An accurate diagnosis of EP location at liver and pelvic wall is totally difficult since its uncommon location. An initial assessment should be based on clinical symptoms and the treatment remains controversial. The surgical management including laparotomy and laparoscopy depends on clinical evaluation, experience of surgeon, and interdisciplinary team. Thus, these abnormal sites of ectopic pregnancy ought to take into consideration for all gynecologists in an emergency condition with a major hemorrhage. CONCLUSIONS: In reproductive age women, primary EP at liver and pelvic wall should be considered with high index of suspicion if intrauterine pregnancy is totally excluded. Timely diagnosis, rational management by surgical excision, and a multidisciplinary team can reduce substantially adverse outcomes

Using Solvent Vapor Annealing for the Enhancement of the Stability and Efficiency of Monolithic Hole-conductor-free Perovskite Solar Cells

In the last few years, perovskite solar cells have attracted enormous interest in the photovoltaic community due to their low cost of materials, tunable band gap, excellent photovoltaic properties and easy process ability at low temperature. In this work, we fabricated hole-conductor-free carbon-based perovskite solar cells with the monolithic structure: glass/FTO/bl-TiO$_{2}$/(mp-TiO$_{2}$/mp-ZrO$_{2}$/mp-carbon) perovskite. The mixed 2D/3D perovskite precursor solution composed of PbI$_{2}$, methylammonium iodide (MAI), and 5-ammoniumvaleric acid iodide (5-AVAI) was drop-casted through triple mesoporous TiO$_{2}$/ZrO$_{2}$/carbon electrode films. We found that the isopropyl alcohol (IPA) solvent vapor annealing strongly influenced on the growth of mixed 2D/3D perovskite on triple mesoscopic layers. It resulted in the better pore filling, better crystalline quality of perovskite layer, thus the improved stability and efficiency of perovskite solar cell was attributed to lower defect concentration and reduced recombination

The Effect of Awareness on the Behavior of Advertisement on Social Network Basis for Cosmetic Products Line

The study examines the factors affecting the perception and interaction behavior with advertising cosmetic products. The authors used SPSS and Smart PLS software to conduct statistics and analyze survey results. The results of data analysis show that there are 5 factors that directly affect the perception of avoidance: Health concerns; Doubts about advertising intermediaries; Privacy concerns; Information value; Obstructing cognitive goals. The factor that directly affects Avoidant Behavior is Perception of avoidance, there are 5 factors that indirectly affect Avoidant Behavior: Health concerns; Doubts about advertising intermediaries; Privacy concerns; Information value; Obstructing cognitive goals. At the same time, the research also shows that negative experiences do not affect the impact process from Avoidant Perception to Avoidant Behavior. This study has important practical elements for businesses, managers and even social network users in reducing users' awareness and avoidance of advertising

Dental-Derived Stem Cells and Their Secretome and Interactions with Bioscaffolds/Biomaterials in Regenerative Medicine: From the In Vitro Research to Translational Applications

Regenerative dentistry is an innovative field of medicine that is growing involving both dental and maxillofacial sciences. Clinical healing occurs when new regenerated tissue is well integrated into the previously damaged host tissue: in this context, the reparative and regenerative actions of resident and recruited mesenchymal stem cells (MSCs) have been thoroughly performed. In the most recent literature, the MSC-produced secretome has been widely studied and it has been even more considered as the strategic promoter of the vast majority of the biological effects derived from stem cell transplantation. Dental-derived mesenchymal stem cells (D-dMSCs) are today considered as an intriguing milestone of the regenerative medicine as such cells have been reported to have a strong ability to differentiate into osteogenic, adipogenic, and chondrogenic lineages, with a peculiar ability to improve the bone mineralization. Complete healing might be achieved by establishing novel strategies, by using scaffolds in combination with oral-derived MSCs in the presence of secretome and growth. The interaction between stem cells and biomaterials is a crucial topic; recent research trends were focused and developed on the interaction both at superficial macroscopic level and at structural microscopic level. About the first ones, involving the researches on scaffold-related macroscopic features, there are evidences that geometrical and mechanical properties of scaffolds are able to influence the cell behavior and their response to differentiating stimulations. Among the manufacturing processes that can be used to fabricate biomimetic scaffolds, the strategy based on the combination of additive manufacturing and computer-aided design (CAD) modelling seems to be one of the most promising. The possibility to design and create any shape for the newly produced scaffolds, and the scientifically confirmed evidence that scaffold geometry plays a crucial role in influencing the MSC response, led researchers towards an increasing attention to scaffold design; more in details, bioengineers designed complex morphologies able to be reproduced on the surfaces of porous biomaterials. Other types of research studies were related to microscopic features of scaffolds, demonstrating that many changes in scaffold microarchitecture modified, for example, the adhesion of stem cells to the scaffold surfaces. The adhesion of stem cells to scaffold is a biologically guided result of complex cellular, physical, and chemical processes, and it is an essential requirement to guarantee a proper and effective tissue engineering aimed to healing and regenerative applications. Differently from the huge number of studies focused on biochemical reactions that trigger stem cell differentiation, very few studies are reported in the scientific literature about how the mechanical environment affects the adhesion of stem cells on biomaterials’ surfaces. We believe that extensive studies will be carried out on this topic in the next few years. However, much still needs to be elucidated in order to be able to create efficient and safe bioartificial substitutes for clinical use

Remark on the Entropy Production of Adaptive Run-and-Tumble Chemotaxis

Chemotactic active particles, such as bacteria and cells, exhibit an adaptive run-and-tumble motion, giving rise to complex emergent behaviors in response to external chemical fields. This motion is generated by the conversion of internal chemical energy into self-propulsion, allowing each agent to sustain a steady-state far from thermal equilibrium and perform works. The rate of entropy production serves as an indicates of how extensive these agents operate away from thermal equilibrium, providing a measure for estimating maximum obtainable power. Here we present the general framework for calculating the entropy production rate created by such population of agents from the first principle, using the minimal model of bacterial adaptive chemotaxis, as they execute the most basic collective action -- the mass transport

PEDESTRIAN ACTIVITY PREDICTION BASED ON SEMANTIC SEGMENTATION AND HYBRID OF MACHINES

The article presents an advanced driver assistance system (ADAS) based on a situational recognition solution and provides alert levels in the context of actual traffic. The solution is a process in which a single image is segmented to detect pedestrians’ position as well as extract features of pedestrian posture to predict the action. The main purpose of this process is to improve accuracy and provide warning levels, which supports autonomous vehicle navigation to avoid collisions. The process of the situation prediction and issuing of warning levels consists of two phases: (1) Segmenting in order to definite the located pedestrians and other objects in traffic environment, (2) Judging the situation according to the position and posture of pedestrians in traffic. The accuracy rate of the action prediction is 99.59% and the speed is 5 frames per second