Simulation of temperature and reaction time prediction of the torrefaction process: case of hard-wood biomass

Direct utilisation of biomass for energy application is less profound due to the problems of low calorific value, high water content, and low grindability of biomass. For this reason, pre-heating treatment, sometimes called torrefaction, is necessary to improve the physical properties of biomass similar to ‘coal-like’ material. Unfortunately, only few comprehensive but simple theoretical models focused on hard-wood biomass were available to describe the torrefaction process. In this discussion, a simple proposed torrefaction model was developed and reported. The model has ability to estimate the yield of product mass and energy after the torrefaction process and determine the optimum conditions.     

Proportional Plus Integral Control for Set-Point Regulation of a Class of Nonlinear RLC Circuits

In this paper we identify graph-theoretic conditions which allow us to write a nonlinear RLC circuit as port-Hamiltonian with constant input matrices. We show that under additional monotonicity conditions on the network’s components, the circuit enjoys the property of relative passivity, an extended notion of classical passivity. The property of relative passivity is then used to build simple, yet robust and globally stable, proportional plus integral controllers. This work was partially supported by CONACyT, México.     

Robustness analysis of systems' safety through a new notion of input‐to‐state safety

In this paper, we propose a new robustness notion that is applicable for certifying systems' safety with respect to external disturbance signals. The proposed input‐to‐state safety notion allows us to certify systems' safety in the presence of the disturbances, which is analogous to the notion of input‐to‐state stability for analyzing systems' stability.     

BETaaS: A Platform for Development and Execution of Machine-to-Machine Applications in the Internet of Things

Wireless Personal Communications - The integration of everyday objects into the Internet represents the foundation of the forthcoming Internet of Things (IoT). Smart objects will be the building...     

Control of cone-jet geometry during electrospray by an electric current

A new electrospray system has been successfully developed by employing a proportional–integral–derivative control action to maintain an electric current at a certain value. A polymer precursor solution containing polyethylene glycol was used to examine the performance of this system. The result showed that cone-jet geometry could be controlled easily by adjusting the electric current. The length of the cone-jet decreased as the electric current was increased, in a correlation that followed power law. We also found that the cone-jet observed during electrospraying was stable and robust with no disturbance during long periods of use (up to 4000 s). The present study is very useful for further development of high precision aerosol generators and particle synthesis.     

Absolute stability analysis of linear systems with Duhem hysteresis operator

In this paper, we investigate the stability of positive and negative feedback interconnections of a linear system and a Duhem hysteresis operator. We provide sufficient conditions on the linear plant and on the Duhem operator which are based on the counterclockwise (CCW) or clockwise (CW) input–output property of the plant and hysteresis operator. We show the application of our main result in the design of a linear controller to stabilize a simple mechanical system driven by a hysteretic actuator, such as, piezo-actuator or smart material-based actuator.     

PID control of second-order systems with hysteresis

The efficacy of proportional, integral and derivative (PID) control for set point regulation and disturbance rejection is investigated in a context of second-order systems with hysteretic components. Two basic structures are studied: in the first, the hysteretic component resides (internally) in the restoring force action of the system (‘hysteretic spring’ effects); in the second, the hysteretic component resides (externally) in the input channel (e.g. piezo-electric actuators). In each case, robust conditions on the PID gains, explicitly formulated in terms of the system data, are determined under which asymptotic tracking of constant reference signals and rejection of constant disturbance signals is guaranteed.     

Current and residual effects of compost and inorganic fertilizer on wheat and soil chemical properties

Restoring soil fertility in smallholder farming systems is essential to sustain crop production. An experiment was conducted in 2011 and 2012 to study the effect of compost and inorganic fertilizer application on soil chemical properties and wheat yield in northwest Ethiopia. Full factorial combinations of four levels of compost (0, 4, 6, 8 t ha^?1) and three levels of inorganic fertilizers (0–0, 17.3–5, 34.5–10 kg N–P ha^?1) were compared in a randomized complete block design with three replications. In 2012, two sets of trials were conducted: one was the repetition of the 2011 experiment on a new experimental plot and the second was a residual effect study conducted on the experimental plots of 2011. Results showed that in the year of application, applying 6 t compost ha^?1 with 34.5–10 kg N–P ha^?1 gave the highest significant grain yield. In the residual effect trial, 8 t compost ha^?1 with 34.5–10 kg N–P ha^?1 gave 271 % increase over the control. Grain protein content increased 21 and 16 % in the current and residual effect trials, respectively, when 8 t compost ha^?1 was applied; it increased 11 and 14 % in the current and residual effect trials, respectively, when 34.5–10 kg N–P ha^?1 was applied. Under the current and residual effects of 8 t compost ha^?1, SOM increased 108 and 104 %; available P 162 and 173 %; exchangeable Ca 16.7 and 17.4 %; and CEC 15.4 and 17.1 %, respectively. Applying 6 t compost ha^?1 with 34.5–10 kg N–P ha^?1 is economically profitable with 844 % MRR.