1,518 research outputs found
A review and analysis of control techniques in HVAC systems
Heating Ventilating and Air Conditioning (HVAC) systems are the core energy-absorbing equipment in buildings. Building HVAC system with effective control technique can greatly reduce energy consumption. The high demand for HVAC system Placing in buildings, using an effective control technique to decrease the energy absorbing of the equipment while meeting the thermal comfort demands in buildings are the most important goals of control designers. The different control methods for HVAC systems. This paper defines control techniques used in HVAC systems, MATLAB/simulation design and implementation of controller’s technique with the transfer function for the HVAC system.
Keywords-HVAC, PID controller, MPC Controller, Adaptive Controller, Fuzzy Controller
Incentive Stackelberg Mean-payoff Games
We introduce and study incentive equilibria for multi-player meanpayoff
games. Incentive equilibria generalise well-studied solution concepts such as
Nash equilibria and leader equilibria (also known as Stackelberg equilibria).
Recall that a strategy profile is a Nash equilibrium if no player can improve
his payoff by changing his strategy unilaterally. In the setting of incentive
and leader equilibria, there is a distinguished player called the leader who
can assign strategies to all other players, referred to as her followers. A
strategy profile is a leader strategy profile if no player, except for the
leader, can improve his payoff by changing his strategy unilaterally, and a
leader equilibrium is a leader strategy profile with a maximal return for the
leader. In the proposed case of incentive equilibria, the leader can
additionally influence the behaviour of her followers by transferring parts of
her payoff to her followers. The ability to incentivise her followers provides
the leader with more freedom in selecting strategy profiles, and we show that
this can indeed improve the payoff for the leader in such games. The key
fundamental result of the paper is the existence of incentive equilibria in
mean-payoff games. We further show that the decision problem related to
constructing incentive equilibria is NP-complete. On a positive note, we show
that, when the number of players is fixed, the complexity of the problem falls
in the same class as two-player mean-payoff games. We also present an
implementation of the proposed algorithms, and discuss experimental results
that demonstrate the feasibility of the analysis of medium sized games.Comment: 15 pages, references, appendix, 5 figure
Thermal Management Of Electronics Experiencing Large Power Dissipation Transients.
Recent developments with micro-porous surfaces have led to the introduction of
very high heat flux boiling surfaces. For example, Wirtz and coworkers have introduced
a structured porous surface that achieves in excess of 1.5MW/m2
in saturated pool boiling
of water at 0.2atm (Tsat = 60°C); and, this increases to 2.1MW/m2
at 1.0atm (Tsat =
100°C). In this case, onset of nucleate boiling (ONB) occurs at approximately 2K
superheat, and the high heat flux noted occurs at 9K superheat, so the boiling curve slope
is very high, approximately 0.3MW/m2
per Kelvin superheat. This suggests that a viable
thermal management approach to systems that experience large transient heat loading
would be to design the heat sink so that the heat sink-to-coolant heat transfer surface
would “ride” its boiling curve. At baseline power dissipation levels, boiling would occur
at near ONB; and, the heat transfer surface would climb the (very steep) boiling curve as
the power dissipation level rises, so that there would be only a moderate electronics
temperature excursion.
Vented (constant pressure), sealed and hybrid immersion cooled electronics
systems are considered. A thermal response model, based on boiling curves having
differing ONB and CHF points (boiling curve slopes) and boiling correlation calculates
the thermal response of the system. Response time constants and maximum temperature
excursions are correlated with boiling curve characteristics, and system geometric and
thermo physical properties.
We have obtained the temperature response with respect to time were obtained
with different system parameters and have been compared with each other
Topology and Size Optimization of Composite Ply Cargo Door
Structural optimization has seen accelerated
deployment throughout all industries in the past
decade, largely due to the recognition that tremendous
efficiency gain can be achieved at concept design stage
through topology optimization. For composite laminate
design a three-phase optimization process is used. The
target of the first phase is the material distribution in
terms of orientation and thickness. This is achieved
through topology optimization where thickness of each
'super-ply' of a unique fiber direction is allowed to
change freely throughout the structure. As a result
thickness contour of each fiber orientation is obtained.
A discrete interpretation of the thickness contour
results in concept design of ply layout and thickness.
Then in Phase-II the interpreted ply-based structural
model is further optimized under all design constraints
with discrete design variables representing the number
of plies of each ply patch. During Phase-III, ply
stacking optimization is performed to refine the design
according to detailed manufacturing constraints. All
manufacturing constraints are considered throughout
all three optimization phases. Such requirement would
translate into percentage requirement during Phase-I
and II so that a balanced distribution of fiber
orientation is achieved to allow feasible stacking
during Phase-III. The three-phase optimization process
is illustrated in this paper. A unique modeling
technique developed in conjunction with the
optimization process is the ply-based finite element
analysis model where ply entities are defined as sets of
elements. Then ply layup is specified by a stack
definition. In the following sections the procedure is
demonstrated for one of the preliminary configurations
developed for the composite cargo door
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