A Wavelet Balance Approach for Steady-State Analysis of Nonlinear Circuits *

In this paper, a novel wavelet balance method is proposed for steady-state analysis of nonlinear circuits. The proposed method presents several merits compared with those conventional frequency domain techniques. First, it has a high convergence rate. Second, it works in time domain so that many critical problems in frequency domain can be handled efficiently. Third, an adaptive scheme exists to automatically select the wavelet basis functions needed at a given accuracy. 1

Effects of nitrogen-phosphorus imbalance on plant biomass production: a global perspective

Background and aimsUnparalleled inputs of anthropogenic nitrogen (N) and phosphorus (P) cause a strong N-P imbalance in terrestrial ecosystems. However, the effects of N-P imbalance on plant biomass production remains unclear.MethodsGiven that tissue N:P ratio may serve as an indicator of plant N or P limitations, we compiled a dataset reporting aboveground biomass (AGB) and tissue N:P ratio simultaneously from worldwide N addition experiments and explored the relationship between the responses of AGB and tissue N:P ratio to N enrichment.ResultsThe N-induced changes in AGB exhibited an asymptotic relationship (i.e., Michaelis-Menten function) with changes in tissue N:P ratio, indicating a progressive P limitation with increasing N. Our results further revealed that plant N and P status was related to the changes in soil inorganic N and P concentrations. Soil N increased while soil P remained unchanged with increasing N rate, thus resulting in an unbalanced soil N and P as N continues to increase.ConclusionsThis study is the first to report the influences of human-induced N-P imbalance on plant biomass production at the global scale. The biomass-N:P ratio relationship needs to be considered for reliable predictions of the future global carbon dynamics under global change

Fuzzy multi-objective linear programming applying to crop area planning

Crop area planning plays significant role in agricultural water management. During the planning, because of ambiguous or uncertain information caused by the vagueness of decision makers' subjective preference or the uncertainty of objective information, conventional multi-objective linear programming (MOLP) model is not suitable for such decision-making in such fuzzy environment. In this study, we proposed the fuzzy multi-objective linear programming (FMOLP) model with triangular fuzzy numbers and transformed the FMOLP model and its corresponding fuzzy goal programming (FGP) problem to crisp ones which can be solved by the conventional programming methods. The FMOLP model was applied to crop area planning of Liang Zhou region, Gansu province of northwest China, and then the optimal cropping patterns under different water-saving levels and satisfaction grades for water resources availability of the decision makers (DM) were obtained. Compared to the MOLP model, the FMOLP model itself expresses the fuzzy information effectively, and its solutions can represent the DMs satisfactory degree of the subjective preference and propose alternative solutions for better decision support when applied in the crop area planning.Fuzzy multi-objective linear programming Fuzzy numbers Fuzzy goal programming Crop area planning

Pre- and Post-silking Carbohydrate Concentrations in Maize Ear-leaves and Developing Ears in Response to Nitrogen Availability

Maize (Zea mays L.) grain yield is considered to be highly associated with carbohydrate dynamics in leaves and developing ears during the critical period bracketing silking. Carbohydrate changes are sensitive to variation in nitrogen (N) availability, yet a comprehensive analysis of the N effect on various carbohydrate concentrations around silking remains elusive. A 2-yr field study was conducted to investigate grain yield, N uptake, ear dry matter and carbohydrate concentrations in ear-leaves and whole ears (prior to silking) and kernels (after silking) of maize grown with 0, 150, and 300 kg N ha(-1). Greater N availability increased maize shoot dry matter and N content at silking and physiological maturity, as well as grain yield. While N had little effect on ear-leaf glucose concentration, sucrose concentration increased but starch concentration decreased with increasing N, regardless of sampling time. Prior to silking, glucose and fructose concentrations in the developing ear responded positively to increasing N availability, but sucrose and starch concentrations declined. In growing kernels shortly after silking, glucose and fructose concentrations in N fertilized treatments were significantly lower than those in the zero-N treatment. In contrast, a significant increase in kernel starch concentration was found in response to 300 kg N ha(-1). These observations point to an important role of the carbohydrate composition of unpollinated ears prior to silking with regard to kernel set and post-silking kernel starch accumulation, and thus final crop yield