Performance Analysis of Skip-Glide Trajectories for Hypersonic Waveriders in Planetary Exploration

A performance analysis for skip and glide is being studied to investigate the potential usage of waverider technology for interplanetary explorations. While the skip and glide equations themselves were first explored by Eggers, this thesis will implement his equations, but then add waverider technology, to determine the possibility of using trajectory assist to navigate around four planets (Earth, Mars, Jupiter and Venus). All trajectory calculations will be based on the waverider lift-to-drag ratios for various planets to determine the maximum range distance. For this research, skip and glide trajectory will be handled separately to determine which is best suited in covering the most distance for a given planet. Ballistic trajectory will only be mentioned in reference to the derivation of the skip trajectory equation, but will not be covered by itself in this research. Hence, it is possible to study a total of 98 cases of skip trajectories, 12 cases of glide trajectories and any additional cases for the four planets. Even though the skip and glide equations bear no planetary effect, all results listed in this research are based on Earth with a waverider lift-to-drag (L/D) ratio of 8.61. For a skip trajectory, the maximum number of skips is set to be 3. A high velocity ratio of 1.0 results in a low incidence angle of 0.1° with the highest range parameter of 3.52 after 3 skips. A low velocity ratio of 0.2, on the other hand, would result in a high incidence of angle of 39.5° with the least range parameter coverage of 0.05. lying the same velocity ratio and lift-to-drag to both skip and glide trajectory calculations result in a big percent difference. For example, a L/D = 8.61 and a velocity ratio (Vf) of 1.0 will have a skip range parameter of 3.52 (22,451.09 km) after 3 skips. The glide range parameter, on the other hand, comes out to be 20.60 (131,389.89 km). The percent increase turns out to be around 485.23%. Based on these numbers, it is clear that using a glide trajectory by itself would gain the most range distance for Earth

Asthma-Related Health Outcomes in New Jersey After a Natural Disaster Event

The occurrence of a natural disaster event such as a hurricane may further hinder the asthma management of asthmatic individuals. Unmanaged asthma has led to increased work absenteeism, preventable emergency department visits, costly hospitalizations and possibly death in severe cases. To improve asthma management in asthmatic adults in New Jersey (NJ) following a natural disaster event, this study examined whether predisposing, enabling and need factors are predictors for asthma exacerbation and asthma-related health care utilization in New Jersey. A retrospective secondary analysis of New Jersey Behavioral Risk Factor Surveillance System (NJBRFSS) data and New Jersey Asthma Call Back Survey (NJACBS) data was conducted on 2011 and 2013 data, which correspond to the pre and post Hurricane Sandy time frame. The Behavioral Model for Vulnerable Populations was used to guide the selection of the disaster-related predisposing, enabling and need risk factors in the study. The data was further stratified into two county comparison groups using the Sandy Community Hardship Index and the Federal Emergency Management Agency (FEMA) Flooding Map to examine the differences in predictors for asthma exacerbation or attacks and asthma-related health care utilization in high impact and low impact county groups. Descriptive statistics, Univariate analyses and Binomial Logistic Regressions were ran using a p-value of 0.05 to determine if there were any statistically significant relationships between the identified risk factors from the conceptual framework and the outcome variables. The study found that at the state level, there are different significant predictors before and after Hurricane Sandy. Perceived cost barrier to medication, being given an asthma management plan and seeing or smelling mold were significant predictors at the state level. Seeing or smelling mold was the only significant predictor for the high impact county group. Overall, this study provided a new conceptual framework and supporting evidence regarding determinants related to asthma exacerbations and asthma-related health care utilization after a natural disaster event in asthmatic adults in NJ. The results of this study can inform public health practice in New Jersey and help improve health education interventions and health policies directed at asthmatic adults after a natural disaster event

Relationship Between Obesity and Periodontal Status in Vietnamese Patients

This study aims to investigate periodontal status, and the relationship between obesity and periodontal status in patients who first visited the Institute of Traditional Medicine, Ho Chi Minh City, Vietnam. 118 patients aged 18 or older, including 56 obese subjects (BMI≥27.5, mean age: 33.8, males: 11, females: 45) and 62 non-obese subjects (BMI<27.5, mean age: 34.3, males: 4, females: 58) were enrolled for a period of 5 months from February 2014 to June 2014. The information on socio-demographic characteristics and dental habits were collected by questionnaire. Periodontal status (PLI, GI, BOP, PD, CAL) was examined and the anthropometric index was measured. There was significantly higher prevalence of periodontitis (39.3%) in the obese group than the non-obese group (16.4%). Means of GI, BOP, PD, and CAL in obese subjects were significantly higher than those in non-obese subjects. Significantly higher percentages of subjects who had lower education, visited dental offices, scaled and polished their teeth regularly were in the non-obese group than in the obese group. Multiple logistic regression analysis revealed that age (OR=3.10), routine of dental visit (OR=3.34) and obesity (OR=2.79) were risk factors significantly related to periodontitis. Periodontal status in obese subjects was poorer than non-obese subjects. Obesity might be the risk factor for periodontitis in Vietnamese patients

A Comprehensive Study on Home Care Needs Among Elderly in an Urban Area of Ho Chi Minh City, Vietnam

Homecare service for elderly has been available in Ho Chi Minh City, Vietnam since 2009, but it is unknown whether homecare needs of elderly are met. Therefore, the objective of the study is to investigate homecare needs among elderly with the aim of providing baseline information to inform policy development to improve homecare services in the city.A cross-sectional study was conducted from 12 July to 12 November, 2015. Three hundred and nine older adults (≥ 60 years old) living in the District 12 of Ho Chi Minh City were randomly chosen and completed interviews using a structured questionnaire. Chi Square tests or ANOVA tests were used to examine the significant associations between elderly characteristics and homecare needs.The mean scores of activities of daily living (ADLs) and instrumental activities of daily living (IADLs) were 5.72 out of 6 and 5.16 out of 8, respectively. The mean score of Affect Balance was 6.23 out of 10. Only 54 of 309 participants (17.48%) had home health care needs, whereas 274 (88.67%) participants had health information needs. Factors having statistically significant associations with homecare needs included older age, male gender, low allowance, living alone and higher number of comorbidities.Elderly in District 12 had low ADLs needs, low psychological needs, low health care needs, but high health information needs and IADLs needs. Services including private care service, chatting service, home health care and health information services may be developed to meet those needs. Keywords: homecare needs, elderly, ADLs, IADL

Vulnerability of Rice Production in Mekong River Delta under Impacts from Floods, Salinity and Climate Change

This study sought to estimate the floods and salinity impact index and climate change vulnerability index for the rice farming provinces in Mekong River Delta. In both indexes, Tra Vinh province and the communes within it have the highest index value, followed by other coastal provinces. The estimation showed that the rice production in these areas are being threatened and will be worsen if there is no appropriate plan to cope with the changes in climate condition and extreme events. The results for the simulation model of paddy yield under different scenarios showed decreases in the paddy yield in Mekong River Delta. Specifically, the yield of Spring paddy decreases 6%, Autumn paddy decreases 2%, Winter paddy decreases 4% and Autumn-winter paddy decreases 4% in 2050. From these results, the climate change adaptation and mitigation policies in this delta is suggested to be focused reducing the exposure to sea level rise; upgrading the irrigation system for paddy planting since the coastal provinces have high rate of rain-fed paddy, vulnerability can also be reduced by enhancing the adaptive capacity of provinces through subsidizing and providing farmers with new paddy varieties which are more tolerant to salinity

Protograph LDPC Code Design For LS-MIMO 1-bit ADC Systems

Recently, two emerging research topics are protograph low-density parity-check (P-LDPC) and large-scale multi-input multi-output (LS-MIMO) with low-resolution analog-to-digital (ADC) converters (LS-MIMO-LOW-ADC). In these directions, many research works have proposed 1-bit ADC as a good candidate for LS-MIMO systems in order to save both transmission power and circuit energy dissipation. However, we observed that previously reported P-LDPC codes might not have good performance for LS-MIMO systems with 1-bit ADC. Hence, we perform a re-design of the P-LDPC codes for the above systems in this paper. The new codes demonstrate a good coding gain from 0:3 dB at rate 1/2 to 0:5 dB at rate 2/3 in different LS-MIMO configurations with 1-bit ADC

Musculoskeletal Pain and Work-related Risk Factors among Waste Collectors in Hanoi, Vietnam: A Cross-sectional Study

BACKGROUND: Musculoskeletal disorders (MSDs) are prevalent among waste collectors (WCs) in developing countries. AIM: This study aimed to investigate the prevalence of MSDs and the factors associated with the risk of persistent musculoskeletal pain among WCs in Hanoi, Vietnam. METHODS: A cross-sectional survey was utilized to study 468 WCs in 2017. The Örebro Musculoskeletal Pain Questionnaire and a questionnaire on demographic and work conditions were used to collect data. Descriptive and multivariate logistics regression analyzes were applied at a significance level of 0.05 to examine the factors related to the risk of persistent pain. FINDINGS: About 74.4% of the participants of this study experienced MSDs in at least one body region and 9.4% reported MSDs in all 10 body sites. The lower back was reported to be the most affected followed by the neck and shoulders. The risk of persistent musculoskeletal pain was significantly associated with age (odds ratio (OR) = 2.31, confidence interval (CI) = 1.05–5.09), gender (OR = 3.29, CI = 1.28–8.44), work hours (OR = 2.35, CI = 1.12–4.92), work shift (OR = 0.48, CI = 0.26–0.92), duration of poor postures of the neck (OR = 0.31, CI = 0.13–0.76), bent back (OR = 0.4 CI = 0.18–0.92) and for medial rotation (OR = 3.01, CI = 1.42–6.36), carrying heavy objects (OR = 2.94, CI = 1.15–7.48), and experience of work dissatisfaction (OR = 3.31, CI = 1.46-7.52), stress (OR = 7.14, CI = 3.14–16.24), or anxiety (OR = 6.37, CI = 3.07–13.21). CONCLUSIONS: High prevalence of MSDs among WCs and its association with self-assessed unfavorable work postures and work-related stress implies the need of mechanical and social support at work for WC to prevent the development of MSDs and persistent pain