197,099 research outputs found
The implications of foreign aid fungibility for development assistance
No full textA foreign aid or foreign lending policy that focuses exclusively on project financing may have unintended consequences, report the authors. New research shows that aid intended for crucial social and economic sectors often merely substitutes for spending that recipient governments would have undertaken anyway and the funds that are thereby freed up are spent for other purposes. If the aid funds something that would have been done anyway, traditional ways of evaluating the aid's effectiveness are not really accurate. Ifaid funds are fungible and the recipient's public spending program is unsatisfactory, project lending may not be cost-effective. If the recipient's public spending program is satisfactory, perhaps the donor should finance a portion of it instead of financing individual projects. One solution to the problem of fungibility, then, is that donors could tie assistance to an overall public spending program (in the recipient country) that provides adequate resources to crucial sectors. To make this kind of reform operational, the authors propose a new lending instrument: a public expenditure reform loan (PERL). A PERL would tie an institution's lending strategy to the recipient country's achievement of mutually agreed-upon development goals. Everyone agrees that better donor coordination is needed, but it has been difficult to achieve because some donors tend to prefer projects (usually with the national flag flying over them). By agreeing on a public expenditure program and financing a portion of it, the World Bank credibly ask other donors to do the same.Payment Systems&Infrastructure,Development Economics&Aid Effectiveness,Gender and Development,Decentralization,Economic Adjustment and Lending,Development Economics&Aid Effectiveness,Poverty Assessment,National Governance,Economic Adjustment and Lending,Public Sector Economics&Finance
Navigation solution for the Texas A&M autonomous ground vehicle
No full textThe need addressed in this thesis is to provide an Autonomous Ground Vehicle (AGV)
with accurate information regarding its position, velocity, and orientation. The system chosen to
meet these needs incorporates (1) a differential Global Positioning System, (2) an Inertial
Measurement Unit consisting of accelerometers and angular-rate sensors, and (3) a Kalman
Filter (KF) to fuse the sensor data. The obstacle avoidance software requires position and
orientation to build a global map of obstacles based on the returns of a scanning laser
rangefinder. The path control software requires position and velocity.
The development of the KF is the major contribution of this thesis. This technology can
either be purchased or developed, and, for educational and financial reasons, it was decided to
develop instead of purchasing the KF software. This thesis analyzes three different cases of
navigation: one-dimensional, two dimensional and three-dimensional (general). Each becomes
more complex, and separating them allows a three step progression to reach the general motion
solution.
Three tests were conducted at the Texas A&M University Riverside campus that
demonstrated the accuracy of the solution. Starting from a designated origin, the AGV traveled
along the runway and then returned to the same origin within 11 cm along the North axis, 19 cm
along the East axis and 8 cm along the Down axis. Also, the vehicle traveled along runway 35R
which runs North-South within 0.1������, with the yaw solution consistently within 1������ of North or
South. The final test was mapping a box onto the origin of the global map, which requires
accurate linear and angular position estimates and a correct mapping transformation
The public sector in the Caribbean : issues and reform options
No full textThe public sector's performance in the Caribbean varies, in reducing poverty and in creating an enabling environment for growth. Barbados and the Bahamas have been the high performers, Guyana and the Dominican Republic have been sluggish, and the other Caribbean countries fall in between. In the Caribbean region, the public sector is now the predominant provider of tertiary education and health services (university education and hospital-based curative care), which mainly benefit the nonpoor. Attempts must be made to recover costs from high-income users and use that revenue to improve the quality and quantity (as appropriate) of basic services. Lessons from experience suggest that most Caribbean countries need to encourage the private sector to participate more in providing infrastructure and need to provide a better regulatory framework. The good news: this is already taking place in many countries.Health Monitoring&Evaluation,Public Health Promotion,Public Sector Economics&Finance,Decentralization,Environmental Economics&Policies,Public Sector Economics&Finance,Health Monitoring&Evaluation,Poverty Assessment,National Governance,Inequality
Stronger Tradeoffs for Orthogonal Range Querying in the Semigroup Model
No full textIn this paper, we focus on lower bounds for data structures supporting orthogonal range querying on m points in n-dimensions in the semigroup model. Such a data structure usually maintains a family of "canonical subsets" of the given set of points and on a range query, it outputs a disjoint union of the appropriate subsets. Fredman showed that in order to prove lower bounds in the semigroup model, it suffices to prove a lower bound on a certain combinatorial tradeoff between two parameters: (a) the total sizes of the canonical subsets, and (b) the total number of canonical subsets required to cover all query ranges. In particular, he showed that the arithmetic mean of these two parameters is Omega(m log^n m). We strengthen this tradeoff by showing that the geometric mean of the same two parameters is Omega(m log^n m).
Our second result is an alternate proof of Fredman's tradeoff in the one dimensional setting. The problem of answering range queries using canonical subsets can be formulated as factoring a specific boolean matrix as a product of two boolean matrices, one representing the canonical sets and the other capturing the appropriate disjoint unions of the former to output all possible range queries. In this formulation, we can ask what is an optimal data structure, i.e., a data structure that minimizes the sum of the two parameters mentioned above, and how does the balanced binary search tree compare with this optimal data structure in the two parameters? The problem of finding an optimal data structure is a non-linear optimization problem. In one dimension, Fredman's result implies that the minimum value of the objective function is Omega(m log m), which means that at least one of the parameters has to be Omega(m log m). We show that both the parameters in an optimal solution have to be Omega(m log m). This implies that balanced binary search trees are near optimal data structures for range querying in one dimension. We derive intermediate results on factoring matrices, not necessarily boolean, while trying to minimize the norms of the factors, that may be of independent interest
Foreign aid's impact on public spending
No full textUsing a model of aid fungibility, the authors examine the relationship between foreign aid and public spending. Based on a panel of cross-country and time-series data, their results show that roughly 75 cents of every dollar given in net development assistance goes to current spending and 25 cents to capital spending in the recipient countries. But concessionary loans - a component of development assistance - stimulate far more government spending. Their results also show that aid increases both public and private investment. To test aid fungibility across both public spending categories, they use a newly constructed data series on the net disbursement of concessionary loans. They find that concessionary loans given to the transport and communication sector are fully nonfungible. But loans to the energy sector are converted into fungible monies and part of the funds leak into transport and communications. Loans to agriculture and education are also fungible. There is no evidence of concessionary funds being diverted for military purposes. Their results show that total public spending in the health sector has no impact on reducing infant mortality, but concessionary loans to the health sector do. This finding leads the authors to conclude that linking foreign aid to an agreed-upon public spending program in areas critical to development might be an effective way to transfer resources to developing countries.Decentralization,Gender and Development,Development Economics&Aid Effectiveness,Public Sector Economics&Finance,Economic Theory&Research,Inequality,Development Economics&Aid Effectiveness,Public Sector Economics&Finance,National Governance,Economic Stabilization
Sensor integration for implementation of obstacle avoidance in an autonomous helicopter system
No full textThis thesis describes the development of the Texas A&M University Autonomous
Helicopter System and the integration of obstacle avoidance capabilities into that system.
The helicopter system, composed of a Bergen Observer helicopter and a Rotomotion
Autonomous Flight Control System (AFCS), was developed as a platform to support the
development of the obstacle avoidance system through integration of sensors and
onboard processing capabilities. The system has proven in various flight tests that it has
the capability to autonomously hover and fly to user defined GPS waypoints. The
obstacle avoidance algorithm has been proven in simulations involving an interface with
the Rotomotion AFCS and the flight simulation software they created to facilitate the
development of that system. The helicopter has also demonstrated appropriate responses
to sensor input commensurate with the obstacle avoidance algorithm. Full avoidance
tests were unable to be performed due to hardware malfunctions inherent in the obstacle
avoidance sensors
A mathematical model for air brake systems in the presence of leaks
No full textThis thesis deals with the development of a mathematical model for an air brake
system in the presence of leaks. Brake systems in trucks are crucial for ensuring
the safety of vehicles and passengers on the roadways. Most trucks in the US are
equipped with S-cam drum brake systems and they are sensitive to maintenance.
Brake defects such as leaks are a major cause of accidents involving trucks. Leaks in
the air brake systems affect braking performance drastically by decreasing the peak
braking pressures attained and also increasing the time required to attain the same,
thereby resulting in longer stopping distances. Hence there is a need for detecting
leaks in an air brake system.
In this thesis, a mathematical model for an air brake system in the presence of
leaks is developed with a view towards developing an automatic leak detection system
in the near future. The model developed here builds on an earlier research at Texas
A&M University in which a "fault free" model of an air brake system is developed,
i.e., a mathematical model of an air brake system that predicts how the pressure in
the brake chamber evolves as a function of the brake pedal input when there are no
leaks in the air brake system.In order to develop a model for an air brake system in
the presence of leaks, one must characterize a "leak". A leak may be characterized by
the location and its size. Since the pipes are short, the location of the leak does not significantly affect the evolution in the brake pressure as much as its size. For this
reason, "effective area" of the leak was chosen as a characteristic of the leak. It was
estimated by fitting an empirical relation for leak with leak flow measurement data.
The supply pressure and effective area of leak comprised the inputs to the model
along with the displacement of the foot pedal (treadle valve plunger). The model was
corroborated with the experimental data collected using the setup at Texas A&M
University
Control and waypoint navigation of an autonomous ground vehicle
No full textThis thesis describes the initial development of the Texas A&M Autonomous
Ground Vehicle test platform and waypoint following software, including the associated
controller design. The original goal of the team responsible for the development of the
vehicle was to enter the DARPA Grand Challenge in October 2005. A 2004 Ford F150
4x4 pickup was chosen as the vehicle platform and was modified with a 6�� suspension
lift and 35�� tires, as well as a commercial drive-by-wire system. The waypoint following
software, the design of which is described in this thesis, is written in C and successfully
drives the vehicle on a course defined by GPS waypoints at speeds up to 50 mph. It uses
various heuristics to determine desired speeds and headings and uses control feedback to
guide the vehicle towards these desired states. A vehicle dynamics simulator was also
developed for software testing. Ultimately, this software will accept commands from
advanced obstacle avoidance software so that the vehicle can navigate in true off-road
terrain
Reading Faces: From Features to Recognition
No full textChang and Tsao recently reported that the monkey face patch system encodes facial identity in a space of facial features as opposed to exemplars. Here, we discuss how such coding might contribute to face recognition, emphasizing the critical role of learning and interactions with other brain areas for optimizing the recognition of familiar faces
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
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