The positive almost periodic solution for Nicholson-type delay systems with linear harvesting terms

AbstractIn this paper, we study the existence and exponential convergence of positive almost periodic solutions for a class of Nicholson-type delay system with linear harvesting terms. Under appropriate conditions, we establish some criteria to ensure that the solutions of this system converge locally exponentially to a positive almost periodic solution. Moreover, we give an example to illustrate our main results

An 8-bit Low Power Energy Recovery Full Adder Design

With the development of wireless communication and portable electronic products, circuit power consumption has become the critical bottleneck of the VLSI design. Among the low power VLSI designs, adiabatic circuit shows a promising future and has been studied by many researchers. As a newly emerged low power technique, adiabatic circuits can be implemented with different architectures such as PAL, 2N-2N2P, ECRL, and CAL, etc. They all lead to significant power saving. In this paper, we implemented true single-phase energy-recovering logic (TSEL) in PSPICE to build a 8-bit low power full adder. In order to verify the power saving of the adiabatic design, a traditional 8-bit static CMOS full adder is also designed in PSPICE for reference. PSPICE power simulation is used to simulate the power consumption of both full adder designs for the same given input pattern sequence. PSPICE power simulation result shows that TSEL full adder lead to effective power saving compared to conventional CMOS full adder. The adiabatic design also shows good potential to be used in high speed circuit design

The cost of ending groundwater overdraft on the North China Plain

Overexploitation of groundwater reserves is a major environmental problem around the world. In many river basins, groundwater and surface water are used conjunctively and joint optimization strategies are required. A hydroeconomic modeling approach is used to find cost-optimal sustainable surface water and groundwater allocation strategies for a river basin, given an arbitrary initial groundwater level in the aquifer. A simplified management problem with conjunctive use of scarce surface water and groundwater under inflow and recharge uncertainty is presented. Because of head-dependent groundwater pumping costs the optimization problem is nonlinear and non-convex, and a genetic algorithm is used to solve the one-step-ahead subproblems with the objective of minimizing the sum of immediate and expected future costs. A real-world application in the water-scarce Ziya River basin in northern China is used to demonstrate the model capabilities. Persistent overdraft from the groundwater aquifers on the North China Plain has caused declining groundwater levels. The model maps the marginal cost of water in different scenarios, and the minimum cost of ending groundwater overdraft in the basin is estimated to be CNY 5.58 billion yr−1. The study shows that it is cost-effective to slowly recover the groundwater aquifer to a level close to the surface, while gradually lowering the groundwater value to the equilibrium at CNY 2.15 m−3. The model can be used to guide decision-makers to economic efficient long-term sustainable management of groundwater and surface water resources