Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed

Development of Risk Uncertainty Factors from Historical NASA Projects

NASA is a good investment of federal funds and strives to provide the best value to the nation. NASA has consistently budgeted to unrealistic cost estimates, which are evident in the cost growth in many of its programs. In this investigation, NASA has been using available uncertainty factors from the Aerospace Corporation, Air Force, and Booz Allen Hamilton to develop projects\u27 risk posture. NASA has no insight into the developmental of these factors and, as demonstrated here, this can lead to unrealistic risks in many NASA Programs and projects (P/p). The primary contribution of this project is the development of NASA missions\u27 uncertainty factors, from actual historical NASA projects, to aid cost-estimating as well as for independent reviews which provide NASA senior management with information and analysis to determine the appropriate decision regarding P/p. In general terms, this research project advances programmatic analysis for NASA projects

Activity Dependent Branching Ratios in Stocks, Solar X-ray Flux, and the Bak-Tang-Wiesenfeld Sandpile Model

We define an activity dependent branching ratio that allows comparison of different time series $X_{t}$. The branching ratio $b_x$ is defined as $b_x= E[\xi_x/x]$. The random variable $\xi_x$ is the value of the next signal given that the previous one is equal to $x$, so $\xi_x=\{X_{t+1}|X_t=x\}$. If $b_x>1$, the process is on average supercritical when the signal is equal to $x$, while if $b_x<1$, it is subcritical. For stock prices we find $b_x=1$ within statistical uncertainty, for all $x$, consistent with an ``efficient market hypothesis''. For stock volumes, solar X-ray flux intensities, and the Bak-Tang-Wiesenfeld (BTW) sandpile model, $b_x$ is supercritical for small values of activity and subcritical for the largest ones, indicating a tendency to return to a typical value. For stock volumes this tendency has an approximate power law behavior. For solar X-ray flux and the BTW model, there is a broad regime of activity where $b_x \simeq 1$, which we interpret as an indicator of critical behavior. This is true despite different underlying probability distributions for $X_t$, and for $\xi_x$. For the BTW model the distribution of $\xi_x$ is Gaussian, for $x$ sufficiently larger than one, and its variance grows linearly with $x$. Hence, the activity in the BTW model obeys a central limit theorem when sampling over past histories. The broad region of activity where $b_x$ is close to one disappears once bulk dissipation is introduced in the BTW model -- supporting our hypothesis that it is an indicator of criticality.Comment: 7 pages, 11 figure

Backpackers Expectation and Satisfaction towards Budget Hotel: a Case Study in Penang

Penang has been the popular cultural heritage tourism attractions in Malaysia. Penang has great potential to develop and offers its cultural and heritage products and experiences to local and foreign visitors. Georgetown is one of the most visited sites in Penang.  Georgetown is awarded the UNESCO listing for its unique architecture and cultural townscape. The variety of cultures on display within the heritage area, such as Muslim, Chinese, Indian and European, is unique to Georgetown. The city is also known as Malaysia's food capital, home to multicultural distinct cuisines, cheap and delicious open-air hawker centers. Apart from that, Georgetown also offers unique and affordable budget hotels to enrich backpacker’s experiences. The main objective of this study is to evaluate the facilities and services provided by budget hotels in Georgetown. The evaluation was based on backpackers’ opinions on the importance and performance rating of the listed attributes. This study adopted the simple random sample method of data collection. About 30 questionnaires were distributed to the backpackers during weekdays and weekends. The socio-demographic data were evaluated using Frequency Analysis. The data showed the different socio-demographic, socio-economic, and trip characteristics of the backpackers. The demographic and trip characteristics data provided the information of visitor’s motivation and activity during their visit to Penang. The Importance-Performance Analysis (IP Analysis) was used to evaluate the overall budget hotels’ facility and service attributes, and the final result has been translated into Importance-Performance action grid. The action grid showed all the 23 attributes of general and specific facilities, and services provided were plotted on the High Importance and Performance quadrant.  Attributes plotted on the action grid showed that all of the attributes were evaluated high on importance and performance suggested that the cultural village management should maintain the status of performance in all attributes area. The Ratio Analysis indicated the ranking of priority which needed special attention from the management of the budget hotels. From the analysis, availability of mini bar, hotel safe box availability, and hotel F&amp;B are value for money were ranked at the highest priority and needed special intention from the management of the budget hotels. Overall, the result of the study was, all of the attributes were evaluated as High Importance and High Performance. The management of the budget hotels in Georgetown has to keep up the good work and maintain the attributes.  Hopefully, the findings of this study will be useful for the management of budget hotels to manage and maintain the facilities and services provided to enhance the quality of backpackers’ experiences.