Multitarget Position-Sensitivity Security Transmission with OAM-DM Based on FDA

The multitarget position-sensitivity security transmission scheme with orbital angular momentum (OAM) directional modulation (DM) waveform using the uniform circular frequency diverse array (FDA) is proposed. The transmitter employs FDA to generate dual-mode range-dependent OAM beam pattern, and the direction information of OAM beam is modulated into the signal. According to the modulation method, orthogonal carrier frequency can be designed to realize multitarget position-dependent OAM pattern. In the undesired position, the intensity pattern and the phase front of the radio beam vary randomly with the digital transmission sequence. Because modulation waveform is position-dependent, the technique offers security, as the signal can be purposely distorted in other positions. The composite dual-mode OAM signal makes it more difficult for eavesdroppers to demodulate correct messages. The receiver with a single antenna employs the phase compensation and helical phase factor to restore the correct digital signal in the desired position. Numerical results show that multitarget position-sensitivity OAM-DM technology based on FDA offers the security transmission scheme.

STUDY ON INFLUENCE OF FACTORS TO ACCEPT THE PRICE OF CONSUMERS: RESEARCH IN THE COMPUTER MARKET IN HO CHI MINH CITY

The research objective focused on addressing the following issues: Does product cohesion impact price acceptability? Does position sensitivity affect price acceptability? How does product knowledge, price understanding, play a role in the relationship of product cohesion and position sensitivity to consumer price adoption?Sample characteristics: Among 605 customer survey samples, there were 400 women, accounting for 66.1% of the total, the remaining 33.9% were male, equivalent to 205 people. The median age in the sample was 27 years old, mostly aged 18-38 years old (accounting for 90.6%). The average income is VND 6.2 million / month, mainly with university degrees (accounting for 74%), coming from districts in the city. The majority of customers using tablet computers are 78.7% of the total, equivalent to 476 people, 21.3% of the remaining use normal computers. Data analysis: Explore factor analysis (EFA), CFA confirmatory factor analysis. The result after EFA is used to evaluate the scale value using a measurement model with CFA. SEM linear structure model is used to test the research hypotheses..

Performance Enhancement of Spaceborne Cooler Passive Launch and On-Orbit Vibration Isolation System

A spaceborne cryogenic cooler induces undesirable microvibration disturbances during its on-orbit operation, which is one of the main sources that degrades the image quality of submeter-level high-resolution observation satellites. Several types of vibration isolation systems based on passive approaches have been developed for reducing the microvibration of the cooler. A coil-spring-type passive vibration isolation system developed in a previous study has shown excellent performance in both launch vibration and on-orbit microvibration isolation. To improve the capability of the conventional cooler isolator, including the position sensitivity and launch vibration reduction, we propose a new version of a dual coil-spring-type passive vibration isolator system. The effectiveness of the newly proposed design was validated through a microjitter measurement test, position sensitivity test, and qualification-level launch vibration test of the isolator.

DEFORMATION RESPONSE OF POLYDIMETHYLSILOXANE SUBSTRATES SUBJECTED TO UNIAXIAL QUASI-STATIC LOADING

To investigate cellular response of cardiomyocytes to substrate mechanics, biocompatible material with stiffness in physiological range is needed. PDMS based material is used for construction of microfluidic organ on chip devices for cell culture due to ease of device preparation, bonding, and possibility of surface functionalization. However it has stiffness orders of magnitude out of physiological range. Therefore, we adapted recently available protocol aiming to prepare substrates which offer stiffness in physiological range 5−100kPa using various mixtures of Sylgard. An in-house developed loading device with single micron position tracking accuracy and sub-micron position sensitivity was adapted for this experimental campaign. All batches of the samples were subjected to uniaxial loading. During quasi-static experiment the samples were compressed to minimally 40% deformation. The results are represented in the form of stress-strain curves calculated from the acquired force and displacement data and elastic moduli are estimated.