Study of Time Delays on a Single Cylinder and a Cylinder in an Array Oscillating in Uniform Flow

Mechanical Engineerin

An Exploration of the Growth Strategies of Small and Medium Technology Start-Up Companies in China

This study aimed to explore the growth strategies used by small and medium sized technology start-up companies in China to acquire customers. This was to determine how Chinese technology start-ups identify customer acquisition strategies and the ways in which they apply them to their business. A qualitative interpretivist approach was undertaken, which encompassed conducting semi-structured in-depth telephone interviews on six owners and senior managers of small and medium sized technology start-ups based in China. An analysis of the interviews using inductive thematic analysis revealed that Chinese technology start-ups use customer acquisition strategies such as social media marketing, paid advertising, word-of-mouth, freemium models, and additional strategies which include free trials, direct marketing and more. This is because they are cost-efficient and convenient strategies that do not require start-ups to utilise extensive resources to implement them. Moreover, the findings of this research indicated that Chinese technology start-ups utilise an array of indicators when choosing customer acquisition strategies for their companies. Indicators such as competitor behaviour, affordability, resource availability, market research and strategy efficiency influenced how they identified strategies. However, the start-ups reported struggling to implement more complex strategies such as pay-per-click which implies that limited resources, a lack of experience and expertise affects the way start-ups implement customer acquisition strategies. Keywords: customer acquisition, small and medium enterprises, technology, start-ups, resource-based view theory

Effect of dual co-rotation wheels configuration on aircraft shimmy

A mathematical model is developed to study the shimmy oscillations of aircraft nose landing gear with a dual-wheel co-rotation configuration. This model incorporates the dynamics of the torsional and lateral mode and the non-linear kinematics of the tire. The procedure of different types of shimmy bifurcation analysis is described in detail. The effect of the co-rotation configuration on shimmy oscillation is compared with non-co-rotation wheels. More specifically, the wheel separation distance and wheel moment of inertia are selected as important parameters to study the effect of the co-rotation configuration on the aircraft shimmy. It is concluded that as the wheel separation distance increases, the lateral shimmy becomes more stable, while the torsional mode become less stable. In comparison to the non-co-rotation configuration, dual co-rotation wheels have a petty effect on landing gear with small wheel separations. However, in the condition of a relatively large distance between wheels, the co-rotation configuration has a great positive influence on the anti-torsional shimmy. The wheel moment inertia, within a practical range, affects shimmy oscillation weakly for both the co-rotation and the non-co-rotation configuration

Analyzing Infrastructure LiDAR Placement with Realistic LiDAR Simulation Library

Recently, Vehicle-to-Everything(V2X) cooperative perception has attracted increasing attention. Infrastructure sensors play a critical role in this research field; however, how to find the optimal placement of infrastructure sensors is rarely studied. In this paper, we investigate the problem of infrastructure sensor placement and propose a pipeline that can efficiently and effectively find optimal installation positions for infrastructure sensors in a realistic simulated environment. To better simulate and evaluate LiDAR placement, we establish a Realistic LiDAR Simulation library that can simulate the unique characteristics of different popular LiDARs and produce high-fidelity LiDAR point clouds in the CARLA simulator. Through simulating point cloud data in different LiDAR placements, we can evaluate the perception accuracy of these placements using multiple detection models. Then, we analyze the correlation between the point cloud distribution and perception accuracy by calculating the density and uniformity of regions of interest. Experiments show that when using the same number and type of LiDAR, the placement scheme optimized by our proposed method improves the average precision by 15%, compared with the conventional placement scheme in the standard lane scene. We also analyze the correlation between perception performance in the region of interest and LiDAR point cloud distribution and validate that density and uniformity can be indicators of performance. Both the RLS Library and related code will be released at https://github.com/PJLab-ADG/LiDARSimLib-and-Placement-Evaluation.Comment: 7 pages, 6 figures, accepted to the IEEE International Conference on Robotics and Automation (ICRA'23

Dahuang Zhechong Pill Combined with Doxorubicin Induces Cell Death through Regulating Energy Metabolism in Human Hepatocellular Carcinoma Cells

Many physiological activities such as cell survival, proliferation, defense, adaptation, and metabolism need to consume energy. Hepatoma cells can quickly start stress responses like multidrug resistance (MDR) requiring adenosine triphosphate (ATP) consumption after administration of chemotherapeutics. We employed CCK-8 assay to evaluate cell viability and the flow cytometry to confirm apoptosis and necrosis. ELISA kit was used to determine intracellular levels of ATP in lysates. Western blot was employed to analyze the expressions of key enzymes involved in energy metabolism. We found that doxorubicin (DOX) potently stimulated apoptosis at a low dose and even induced necrosis at a high dose in SMMC-7721. DHZCP combined with DOX at low or middle dose enhanced the synergistic antihepatoma effect. Results indicated that Dahuang Zhechong Pill (DHZCP) inhibited the expressions of several key enzymes involved in oxidative phosphorylation and reduced intracellular ATP levels. The combination of DHZCP with DOX reversed the elevation of intracellular ATP levels, and a significantly synergistic antitumor effect was observed. DHZCP could not only strengthen the therapeutic effects of chemotherapeutic drugs but also decrease the doses of chemotherapeutic drugs and the incidences of adverse reactions, providing novel strategies for clinical treatment of liver cancer

PO-173 The Effects of Interval Exercise on oxidative stress and Smyd1-related myocardial hypertrophy in Rats with Myocardial Infarction

Objective This study was carried out to investigate interval exercise on Smyd1 expression and F-actin sarcomere assembly in non-infarcted myocardium of normal and myocardial infarction(MI) rats and its possible mechanism. Methods Male SD rats were randomly divided into normal control group (C), normal interval exercise group (CE), sham-operated group (S), MI group (MI), MI with interval exercise group (ME) and MI with ROS Tempol group (MT), n=10. MI model was established by left anterior descending coronary artery ligation. Interval exercise was carried out on a small animal treadmill. MT group was given an oral solution of Tempol (2mmol/L). Hemodynamics was performed to evaluate cardiac function. HE and Masson staining were used to analyze the cross-sectional area (CSA) of cardiomyocytes and collagen volume fraction, respectively. T-SOD and MDA kits were used to detect oxidative stress. H9C2 cells were treated with H2O2. Immunofluorescence staining was used to determine Smyd1 expression and F-actin sarcomere assembly. RT-qPCR and Western blotting were used to detect the gene or protein expression of Smyd1, Trx1, Hsp90, MuRF1, cTnI, α-actinin and BNP. Results Smyd1, Trx1, Hsp90, MuRF1 and BNP expression in the peri-infarcted area were up-regulated, but cTnI and α-actinin expression and F-actin assembly were decreased. The cardiac function was reduced. Both interval exercise and Tempol intervention significantly increase the CSA and expression of Smyd1, Trx1, cTnI and α-actinin, improve the antioxidation capacity and F-actin sarcomere assembly and cardiac function, reduce the expression of Hsp90, MuRF1, BNP and ROS level, and inhibit the fibrosis of myocardium. The oxidative stress level was closely related to the Smyd1 expression. Improvement of cardiac function were correlated with Smyd1 expression. H2O2 can induce oxidative stress injuries of H9C2, and its closely related to cardiomyocytes oxidative stress level and Smyd1 expression. Conclusions Interval exercise could promote antioxidant capability and physiological cardiomyocyte hypertrophy, regulate the expression of Smyd1, Hsp90 and MuRF1 in infarcted heart; so as to improve the cardiac function. Smyd1 may participate in pathologic hypertrophy of cardiomyocytes caused by oxidative stress