Process-based mass-balance modeling of soil phosphorus availability in a grassland fertilized with N and P

Modeling changes in plant-available soil P in relation to P budgets should integrate the isotopic kinetic approach, which describes the dynamics of P ion transfer at the solid-to-solution interface. We tested a process-based mass-balance model that uses the quantity of P ions in solution, the diffusive P ions (Pr) in the solid phase, and the annual P budget to describe the soil P availability of a timothy (Phleum pratense L.) grassland that received additions of annual P and N fertilizer. An experiment was established on a gravely-sandy loam soil in 1998, with combinations of P (0, 15, 30, and 45 kg ha^?1) and N (0, 60, 120, and 180 kg ha^?1) applied annually from 1999 to 2006. An isotopic dilution analysis was performed on soils sampled in 2006 to calibrate the Freundlich kinetic equation which describes the dynamics of Pr transfer at the solid-to-solution interface as a function of time (t) and concentration of P ions in solution (Cp). Model simulations were performed over 9 years (1999–2007). Measurements of Cp from soils sampled between 2001 and 2007 were compared with simulated values to evaluate model performance. The amount of Pr was estimated for two transfer periods, of 2 and 3 months, to evaluate the extent and contribution of slow P ion reactions. The Freundlich kinetic equation was defined as: Pr = 7.78 × Cp^0.41 × t ^0.36 (with Pr < Pr_LIMIT, 192 observations, Adj. R ² = 1.0, P < 0.001). Simulated Pr values were 74 and 84% of total inorganic soil P for the transfer periods of 2 and 3 months, respectively. For the two transfer periods, and for each combination of N and P additions, simulations accurately reflected the long-term effects of P and N fertilization on the trends of measured Cp with root mean square deviation (RMSD) between measured and simulated values of less than 0.17. Across P applications, the simulations were slightly improved with a 2-month transfer period for limiting N conditions (0 and 60 kg N ha^?1; Y = 0.95X + 0.06, R² = 0.76, RMSD = 0.08) and a 3-month transfer period for non-limiting conditions (120 and 180 kg N ha^?1; Y = 0.86X + 0.04, R² = 0.78, RMSD = 0.06). This approach needs to be tested in various soil types and diverse cropping systems because the estimation of Pr value can be quite sensitive to the extent of rapid and slow reactions, hence the transfer periods. For this gravely-sandy loam soil, the proposed approach accurately describes the functioning of P cycling and confirms the agronomic importance of solution and solid phase P ions in managed grasslands.     

The production of biohydrogen by a novel strain Clostridium sp. YM1 in dark fermentation process

In view of increasing attempts for the production of renewable energy, the production of biohydrogen energy by a new mesophilic bacterium Clostridium sp. YM1 was performed for the first time in the dark fermentation. Experimental results showed that the fermentative hydrogen was successfully produced by Clostridium sp. YM1 with the highest cumulative hydrogen volume of 3821 ml/L with a hydrogen yield of 1.7 mol H₂/mol glucose consumed. Similar results revealed that optimum incubation temperature and pH value of culture medium were 37 °C and 6.5, respectively. The study of hydrogen production from glucose and xylose revealed that this strain was able to generate higher hydrogen from glucose compared to that from xylose. The profile of volatile fatty acids produced showed that hydrogen generation by Clostridium sp. YM1 was butyrate-type fermentation. Moreover, the findings of this study indicated that an increase in head space of fermentation culture positively enhanced hydrogen production.     

Robust Model-Free Control Applied to a Quadrotor UAV

The objective of this paper is to deal with a new technique based on Model-Free Control (MFC). The concept of this controller is to use a basic controller along with an ultra-local model to compensate for system’s uncertainties and disturbances. In this paper, a proposed algorithm is introduced based on an integrated structure between the Nonlinear Integral-Backstepping technique (NIB) and the MFC. The LQR, NIB, LQR-MFC, and NIB-MFC are implemented on a real quadrotor UAV. Various real-time flight tests are conducted to validate the importance of using the MFC side by side with NIB. The proposed combination shows robust performance compared to the other algorithms under fault-free and actuator fault conditions.     

Skewed general variable neighborhood search for the cumulative capacitated vehicle routing problem

The cumulative capacitated vehicle routing problem (CCVRP) is a relatively new version of the classical capacitated vehicle routing problem, and it is equivalent to a traveling repairman problem with capacity constraints and a homogeneous vehicle fleet, which aims to minimize the total arrival time at customers. Many real‐world applications can be modeled by this problem, such as the important application resulting from the humanitarian aid following a natural disaster. In this paper, two heuristics are proposed. The first one is a constructive heuristic to generate an initial solution and the second is the skewed variable neighborhood search (SVNS) heuristic. The SVNS algorithm starts with the initial solution. At each iteration, the perturbation phase and the local search phase are used to improve the solution of the CCVRP, and the distance function in acceptance criteria phase is used to improve the exploration of faraway valleys. This algorithm is applied to a set of benchmarks, and the comparison results show that the proposed algorithms provide better solutions than those reported in the previous literature on memetic algorithms and adaptive large neighborhood search heuristics.     

A new efficient lightweight and secure image cipher scheme

Multimedia Tools and Applications - The protection of multimedia content has become a key area of research, since very often a user’s privacy and confidentiality can be at risk. Although a...     

Engineering Lipid Bilayer Membranes for Protein Studies

Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques.     

Color thresholds for aesthetically compatible replacement of stones on monuments

A visual test was conducted to find color ranges in which a replacement stone is aesthetically compatible. This study describes a color calibrated image chain processing, from acquisition to display, that was used to simulate stone replacements on a realistic image of monument. Then, a visual test protocol was designed to locate color thresholds that separate a perceptible from an imperceptible replaced stone. A case study has been performed on the Aigues‐Mortes medieval city walls (South of France): Fifteen naive observers rated 2160 proposals of simulated stone replacements. The observer's answers (acceptance or rejection) were used to compute color thresholds along three colorimetric axes in a physiological and device‐independent color space (LMS). The results show that color thresholds are not centered on the mean color of the monument. Furthermore, lighter colors are not accepted, though these appear in the original wall. These color thresholds constitute a set of quantitative criteria for aesthetically compatible stones. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 356–363, 2013     

Enzymatic production of biodiesel from used/waste vegetable oils: Design of a pilot plant

In this work, a proposed pilot plant has been designed to produce 1 ton h^?1 biodiesel (BD) from waste/used vegetable oil using enzymatic approach. Complete material and energy balances were carried out using Excel spreadsheets, and detailed equipment sizing were determined. Immobilized lipase (Novozyme 435) is used as a catalyst in a packed bed bioreactor. The effluent of the reactor is passed though a Liquid–liquid extractor to separate the BD from other components. This is followed by a flash dram and a vacuum distillation column for further purification of the product. In addition, an economic feasibility of this process was assessed. The amount of feed streams of waste oil, methanol and tert-butanol required were found to be 1138, 130 and 7.6 kg h^?1, respectively. The main units in the proposed plant were designed and the economic feasibility of the process was assessed. It was found that the total capital investment required is about US$ 620,000, which will be paid back within four years of operation.     

Sensor network design for complex systems

This paper proposes a strategy to design a minimal and fault‐tolerant sensor network for observability of complex systems. Complex systems are large‐scale dynamic systems composed of interconnected subsystems. The objective is to determine the sensors to be used so that the system is observable while minimizing the number of sensors. The strategy is based on breaking down complex systems into interconnected subsystems. System breakdown helps in treating each subsystem separately and allows using reduced‐order observers rather than a large‐scale observer for the overall system. An academic example is given to illustrate the proposed strategy.Copyright © 2011 John Wiley & Sons, Ltd.