Abstract: In this letter, we considers a delayed predatory-prey system with Holling type II functional response. Under some sufficient conditions, the existence of multiple positive periodic solutions is obtained by using Mawhin’s continuation theorem of coincidence degree theory. An example is given to illustrate the effectiveness of our results.
Abstract: By utilizing the comparison theorem and Lyapunov
second method, some sufficient conditions for the permanence and
global attractivity of positive periodic solution for a predator-prey
model with mutual interference m ∈ (0, 1) and delays τi are
obtained. It is the first time that such a model is considered with
delays. The significant is that the results presented are related to the
delays and the mutual interference constant m. Several examples are
illustrated to verify the feasibility of the results by simulation in the
last part.
Abstract: This paper investigates the impact on operating time delay and relay maloperation when 1st,2nd and 3rd order analog antialiasing filters are used in numerical distance protection. RC filter with cut-off frequency 90 Hz is used. Simulations are carried out for different SIR (Source to line Impedance Ratio), load, fault type and fault conditions using SIMULINK, where the voltage and current signals are fed online to the developed numerical distance relay model. Matlab is used for plotting the impedance trajectory. Investigation results shows that, about 75 % of the simulated cases, numerical distance relay operating time is not increased even-though there is a time delay when higher order filters are used. Relay maloperation (selectivity) also reduces (increases) when higher order filters are used in numerical distance protection.
Abstract: We give an explicit formula for the general solution of a one dimensional linear delay differential equation with multiple delays, which are integer multiples of the smallest delay. For an equation of this class with two delays, we derive two equations with single delays, whose stability is sufficient for the stability of the equation with two delays. This presents a new approach to the study of the stability of such systems. This approach avoids requirement of the knowledge of the location of the characteristic roots of the equation with multiple delays which are generally more difficult to determine, compared to the location of the characteristic roots of equations with a single delay.
Abstract: In this paper, a FitzHugh-Nagumo model with time delays is investigated. The linear stability of the equilibrium and the existence of Hopf bifurcation with delay τ is investigated. By applying Nyquist criterion, the length of delay is estimated for which stability continues to hold. Numerical simulations for justifying the theoretical results are illustrated. Finally, main conclusions are given.
Abstract: In this paper, a delayed Nicholson,s blowflies model with a linear harvesting term is investigated. Regarding the delay as a bifurcation parameter, we show that Hopf bifurcation will occur when the delay crosses a critical value. Numerical simulations supporting the theoretical findings are carried out.
Abstract: We examined the effects of the sowing time on the yield production and oil content of the sunflower hybrids in 2010 and 2012. The crop year and the sowing time had both a strong impact on the yield, on the oil- content and yield. By delaying the sowing time both the yield crop result and the oil yield increased. In 2010 in terms of crop yield and oil yield results PR64H42 was the best, in 2012 NK Neoma, in all three sowing times. The oil content of the hybrids was better in 2010. The highest oil content was recorded at early sowing time. We found out that the hybrid had a stronger impact in 2010 on both crop yield result and on oil content than in 2012. The sowing time played a bigger role regarding yield results in 2012. In addition the sowing time influenced oil content development highly.
Abstract: This paper deals with design of walking beam pendel
axle suspension system. This axles and suspension systems are
mainly required for transportation of heavy duty and Over Dimension
Consignment (ODC) cargo, which is exceeding legal limit in terms of
length, width and height. Presently, in Indian transportation industry,
ODC movement growth rate has increased in transportation of bridge
sections (pre-cast beams), transformers, heavy machineries, boilers,
gas turbines, windmill blades etc. However, current Indian standard
road transport vehicles are facing lot of service and maintenance
issues due to non availability of suitable axle and suspension to carry
the ODC cargoes. This in turn will lead to increased number of road
accidents, bridge collapse and delayed deliveries, which finally result
in higher operating cost. Understanding these requirements, this work
was carried out. These axles and suspensions are designed for
optimum self – weight with maximum payload carrying capacity with
better road stability.
Abstract: In this paper we propose a necessary condition for the existence of chaos in delay differential equations of fractional order. To explain the proposed theory, we discuss fractional order Liu system and financial system involving delay.
Abstract: This paper presents CMOS Current Mode Logic (CML) circuits for a high speed Digital to Analog Converter (DAC) using standard CMOS 65nm process. The CML circuits have the propagation delay advantage over its conventional CMOS counterparts due to smaller output voltage swing and tunable bias current. The CML circuits proposed in this paper can achieve a maximum propagation delay of only 9.3ps, which can satisfy the stringent requirement for the 5 GHz high speed DAC application. Another advantage for CML circuits is its dynamic symmetry characteristic resulting in a reduction of an additional inverter. Simulation results show that the proposed CML circuits can operate from 1.08V to 1.3V with temperature ranging from -40 to +120°C.
Abstract: This paper presents a 14-bit cyclic-pipelined Analog to digital converter (ADC) running at 1 MS/s. The architecture is based on a 1.5-bit per stage structure utilizing digital correction for each stage. The ADC consists of two 1.5-bit stages, one shift register delay line, and digital error correction logic. Inside each 1.5-bit stage, there is one gain-boosting op-amp and two comparators. The ADC was implemented in 0.18µm CMOS process and the design has an area of approximately 0.2 mm2. The ADC has a differential input range of 1.2 Vpp. The circuit has an average power consumption of 3.5mA with 10MHz sampling clocks. The post-layout simulations of the design satisfy 12-bit SNDR with a full-scale sinusoid input.
Abstract: In this paper, a robust decentralized congestion control strategy is developed for a large scale network with Differentiated Services (Diff-Serv) traffic. The network is modeled by a nonlinear fluid flow model corresponding to two classes of traffic, namely the premium traffic and the ordinary traffic. The proposed congestion controller does take into account the associated physical network resource limitations and is shown to be robust to the unknown and time-varying delays. Our proposed decentralized congestion control strategy is developed on the basis of Diff-Serv architecture by utilizing a robust adaptive technique. A Linear Matrix Inequality (LMI) condition is obtained to guarantee the ultimate boundedness of the closed-loop system. Numerical simulation implementations are presented by utilizing the QualNet and Matlab software tools to illustrate the effectiveness and capabilities of our proposed decentralized congestion control strategy.
Abstract: Signature amortization schemes have been introduced
for authenticating multicast streams, in which, a single signature is
amortized over several packets. The hash value of each packet is
computed, some hash values are appended to other packets, forming
what is known as hash chain. These schemes divide the stream into
blocks, each block is a number of packets, the signature packet in
these schemes is either the first or the last packet of the block.
Amortization schemes are efficient solutions in terms of computation
and communication overhead, specially in real-time environment.
The main effictive factor of amortization schemes is it-s hash chain
construction. Some studies show that signing the first packet of each
block reduces the receiver-s delay and prevents DoS attacks, other
studies show that signing the last packet reduces the sender-s delay.
To our knowledge, there is no studies that show which is better, to
sign the first or the last packet in terms of authentication probability
and resistance to packet loss.
In th is paper we will introduce another scheme for authenticating
multicast streams that is robust against packet loss, reduces the
overhead, and prevents the DoS attacks experienced by the receiver
in the same time. Our scheme-The Multiple Connected Chain signing
the First packet (MCF) is to append the hash values of specific
packets to other packets,then append some hashes to the signature
packet which is sent as the first packet in the block. This scheme
is aspecially efficient in terms of receiver-s delay. We discuss and
evaluate the performance of our proposed scheme against those that
sign the last packet of the block.
Abstract: Mostly, pedestrian-car accidents occurred at a
signalized interaction is because pedestrians cannot across the
intersection safely within the green light. From the viewpoint of
pedestrian, there might have two reasons. The first one is pedestrians
cannot speed up to across the intersection, such as the elders. The other
reason is pedestrians do not sense that the signal phase is going to
change and their right-of-way is going to lose. Developing signal logic
to protect pedestrian, who is crossing an intersection is the first
purpose of this study. Another purpose of this study is improving the
reliability and reduce delay of public transportation service. Therefore,
bus preemption is also considered in the designed signal logic. In this
study, the traffic data of the intersection of Chong-Qing North Road
and Min-Zu West Road, Taipei, Taiwan, is employed to calibrate and
validate the signal logic by simulation. VISSIM 5.20, which is a
microscopic traffic simulation software, is employed to simulate the
signal logic. From the simulated results, the signal logic presented in
this study can protect pedestrians crossing the intersection
successfully. The design of bus preemption can reduce the average
delay. However, the pedestrian safety and bus preemptive signal will
influence the average delay of cars largely. Thus, whether applying the
pedestrian safety and bus preemption signal logic to an isolated
intersection or not should be evaluated carefully.
Abstract: IP networks are evolving from data communication
infrastructure into many real-time applications such as video
conferencing, IP telephony and require stringent Quality of Service
(QoS) requirements. A rudimentary issue in QoS routing is to find a
path between a source-destination pair that satisfies two or more endto-
end constraints and termed to be NP hard or complete. In this
context, we present an algorithm Multi Constraint Path Problem
Version 3 (MCPv3), where all constraints are approximated and
return a feasible path in much quicker time. We present another
algorithm namely Delay Coerced Multi Constrained Routing
(DCMCR) where coerce one constraint and approximate the
remaining constraints. Our algorithm returns a feasible path, if exists,
in polynomial time between a source-destination pair whose first
weight satisfied by the first constraint and every other weight is
bounded by remaining constraints by a predefined approximation
factor (a). We present our experimental results with different
topologies and network conditions.
Abstract: This paper describes the design of new method of
propagation delay measurement in micro and nanostructures during
characterization of ASIC standard library cell. Providing more
accuracy timing information about library cell to the design team we
can improve a quality of timing analysis inside of ASIC design flow
process. Also, this information could be very useful for semiconductor
foundry team to make correction in technology process. By
comparison of the propagation delay in the CMOS element and result
of analog SPICE simulation. It was implemented as digital IP core for
semiconductor manufacturing process. Specialized method helps to
observe the propagation time delay in one element of the standard-cell
library with up-to picoseconds accuracy and less. Thus, the special
useful solutions for VLSI schematic to parameters extraction, basic
cell layout verification, design simulation and verification are
announced.
Abstract: The Mobile IP Standard has been developed to support mobility over the Internet. This standard contains several drawbacks as in the cases where packets are routed via sub-optimal paths and significant amount of signaling messages is generated due to the home registration procedure which keeps the network aware of the current location of the mobile nodes. Recently, a dynamic hierarchical mobility management strategy for mobile IP networks (DHMIP) has been proposed to reduce home registrations costs. However, this strategy induces a packet delivery delay and increases the risk of packet loss. In this paper, we propose an enhanced version of the dynamic hierarchical strategy that reduces the packet delivery delay and minimizes the risk of packet loss. Preliminary results obtained from simulations are promising. They show that the enhanced version outperforms the original dynamic hierarchical mobility management strategy version.
Abstract: This paper studies the effect of time delay on stability
of mutualism population model with limited resources for both
species. First, the stability of the model without time delay is
analyzed. The model is then improved by considering a time delay in
the mechanism of the growth rate of the population. We analyze the
effect of time delay on the stability of the stable equilibrium point.
Result showed that the time delay can induce instability of the stable
equilibrium point, bifurcation and stability switches.
Abstract: This paper describes identification of the two poles
unstable SOPDT process, especially with large time delay. A new
modified relay feedback identification method for two poles unstable
SOPDT process is proposed. Furthermore, for the two poles unstable
SOPDT process, an additional Derivative controller is incorporated
parallel with relay to relax the constraint on the ratio of delay to the
unstable time constant, so that the exact model parameters of
unstable processes can be identified. To cope with measurement
noise in practice, a low pass filter is suggested to get denoised output
signal toimprove the exactness of model parameter of unstable
process. PID Lead-lag tuning formulas are derived for two poles
unstable (SOPDT) processes based on IMC principle. Simulation
example illustrates the effectiveness and the simplicity of the
proposed identification and control method.
Abstract: The aim of this paper is to present a new
three-dimensional proportional-pursuit coupled (PP) guidance law to
track highly maneuverable aircraft. Utilizing a 3-D polar coordinate frame, the PP guidance law is formed by collecting proportional
navigation guidance in Z-R plane and pursuit guidance in X-Y plane.
Feedback linearization control method to solve the guidance
accelerations is used to implement PP guidance. In order to
compensate the actuator time delay, the time delay compensated
version of PP guidance law (CPP) was derived and proved the
effectiveness of modifying the problem of high acceleration in the final
phase of pursuit guidance and improving the weak robustness of
proportional navigation. The simulation results for intercepting Max G
turn situation show that the proposed proportional-pursuit coupled
guidance law guidance law with actuator delay compensation (CPP)
possesses satisfactory robustness and performance.