661 research outputs found
Design Optimization of Gas Generator Hybrid Propulsion Boosters
A methodology used in support of a study for NASA/MSFC to optimize the design of gas generator hybrid propulsion booster for uprating the National Space Transportation System (NSTS) is presented. The objective was to compare alternative configurations for this booster approach, optimizing each candidate concept on different bases, in order to develop data for a trade table on which a final decision was based. The methodology is capable of processing a large number of independent and dependent variables, adjusting the overall subsystems characteristics to arrive at a best compromise integrated design to meet various specific optimization criteria subject to selected constraints. For each system considered, a detailed weight statement was generated along with preliminary cost and reliability estimates
QUALITY MANAGEMENT IN A CHANGING ORGANIZATIONAL ENVIRONMENT: LOOKING FOR NEW CONVERSATION TOOLS
Teaching/Communication/Extension/Profession,
Soft Handoff and Uplink Capacity in a Two-Tier CDMA System
This paper examines the effect of soft handoff on the uplink user capacity of
a CDMA system consisting of a single macrocell in which a single hotspot
microcell is embedded. The users of these two base stations operate over the
same frequency band. In the soft handoff scenario studied here, both macrocell
and microcell base stations serve each system user and the two received copies
of a desired user's signal are summed using maximal ratio combining. Exact and
approximate analytical methods are developed to compute uplink user capacity.
Simulation results demonstrate a 20% increase in user capacity compared to hard
handoff. In addition, simple, approximate methods are presented for estimating
soft handoff capacity and are shown to be quite accurate.Comment: To appear in IEEE Transactions on Wireless Communication
Uplink Throughput in a Single-Macrocell/Single-Microcell CDMA System, with Application to Data Access Points
This paper studies a two-tier CDMA system in which the microcell base is
converted into a data access point (DAP), i.e., a limited-range base station
that provides high-speed access to one user at a time. The microcell (or DAP)
user operates on the same frequency as the macrocell users and has the same
chip rate. However, it adapts its spreading factor, and thus its data rate, in
accordance with interference conditions. By contrast, the macrocell serves
multiple simultaneous data users, each with the same fixed rate. The
achieveable throughput for individual microcell users is examined and a simple,
accurate approximation for its probability distribution is presented.
Computations for average throughputs, both per-user and total, are also
presented. The numerical results highlight the impact of a desensitivity
parameter used in the base-selection process.Comment: To appear in IEEE Transactions on Wireless Communication
Uplink User Capacity in a CDMA System with Hotspot Microcells: Effects of Finite Transmit Power and Dispersion
This paper examines the uplink user capacity in a two-tier code division
multiple access (CDMA) system with hotspot microcells when user terminal power
is limited and the wireless channel is finitely-dispersive. A
finitely-dispersive channel causes variable fading of the signal power at the
output of the RAKE receiver. First, a two-cell system composed of one macrocell
and one embedded microcell is studied and analytical methods are developed to
estimate the user capacity as a function of a dimensionless parameter that
depends on the transmit power constraint and cell radius. Next, novel
analytical methods are developed to study the effect of variable fading, both
with and without transmit power constraints. Finally, the analytical methods
are extended to estimate uplink user capacity for multicell CDMA systems,
composed of multiple macrocells and multiple embedded microcells. In all cases,
the analysis-based estimates are compared with and confirmed by simulation
results.Comment: To appear in IEEE Transactions on Wireless Communication
The Farmer Took Another Load Away! Hay! Hay!
Illustration of famer pulling hay on horse drawn carriage; Photo of two menhttps://scholarsjunction.msstate.edu/cht-sheet-music/10440/thumbnail.jp
The Freckle Song.
Photo of man; City scape in backgroundhttps://scholarsjunction.msstate.edu/cht-sheet-music/10445/thumbnail.jp
Social Work Faculty Perceptions of the Leadership Qualities of Their Academic Leaders
Leadership within the social work academic setting is unique and complex. Understanding the way in which faculty members experience the leadership qualities of their academic leaders is a necessary precursor to effective leadership development. This article reports on the quantitative data from a mixed-methods, nationwide survey exploring social work faculty perceptions of the leadership qualities of their academic programs\u27 leaders
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