Causes of breakage and disruption in a homogeniser

Many authors have written in the past regarding the exact causes of breakage and disruption in a high pressure homogeniser, but there has been little agreement. This paper investigates some of the most likely causes of the rupture of the walls of unicellular organisms and offers suggestions obtained from various papers and work carried out

Intermittent predictive control of an inverted pendulum

Intermittent predictive pole-placement control is successfully applied to the constrained-state control of a prestabilised experimental inverted pendulum

Embedded Model Control calls for disturbance modeling and rejection

Robust control design is mainly devoted to guaranteeing the closed-loop stability of a model-based control law in the presence of parametric uncertainties. The control law is usually a static feedback law which is derived from a (nonlinear) model using different methodologies. From this standpoint, stability can only be guaranteed by introducing some ignorance coefficients and restricting the feedback control effort with respect to the model-based design. Embedded Model Control shows that, the model-based control law must and can be kept intact in the case of uncertainty, if, under certain conditions, the controllable dynamics is complemented by suitable disturbance dynamics capable of real-time encoding the different uncertainties affecting the ‘embedded model', i.e. the model which is both the design source and the core of the control unit. To be real-time updated the disturbance state is driven by an unpredictable input vector, the noise, which can only be estimated from the model error. The uncertainty-based (or plant-based) design concerns the noise estimator, so as to prevent the model error from conveying uncertainty components (parametric, cross-coupling, neglected dynamics) which are command-dependent and thus prone to destabilizing the controlled plant, into the embedded model. Separation of the components in the low and high frequency domain by the noise estimator itself allows stability recovery and guarantee, and the rejection of low frequency uncertainty components. Two simple case studies endowed with simulated and experimental runs will help to understand the key assets of the methodolog

Offset-free receding horizon control of constrained linear systems

The design of a dynamic state feedback receding horizon controller is addressed, which guarantees robust constraint satisfaction, robust stability and offset-firee control of constrained linear systems in the presence of time-varying setpoints and unmeasured disturbances. This objective is obtained by first designing a dynamic linear offset-free controller and computing an appropriate domain of attraction for this controller. The linear (unconstrained) controller is then modified by adding a perturbation term, which is computed by a (constrained) robust receding horizon controller. The receding horizon controller has the property that its domain of attraction contains that of the linear controller. In order to ensure robust constraint satisfaction, in addition to offset-free control, the transient, as well as the limiting behavior of the disturbance and setpoint need to be taken into account in the design of the receding horizon controller. The fundamental difference between the results and the existing literature on receding horizon control is that the transient effect of the disturbance and set point sequences on the so-called "target calculator" is explicitly incorporated in the formulation of the receding horizon controller. An example of the control of a continuous stirred-tank reactor is presented. (c) 2005 American Institute of Chemical Engineers

State Space Realization of Model Predictive Controllers Without Active Constraints

To enable the use of traditional tools for analysis of multivariable controllers such as model predictive control (MPC), we develop a state space formulation for the resulting controller for MPC without constraints or assuming that the constraints are not active. Such a derivation was not found in the literature. The formulation includes a state estimator. The MPC algorithm used is a receding horizon controller with infinite horizon based on a state space process model. When no constraints are active, we obtain a state feedback controller, which is modified to achieve either output tracking, or a combination of input and output tracking. When the states are not available, they need to be estimated from the measurements. It is often recommended to achieve integral action in a MPC by estimating input disturbances and include their effect in the model. We show that to obtain offset free steady state the number of estimated disturbances must equal the number of measurements. The estimator is included in the controller equation, and we obtain a formulation of the overall controller with the set-points and measurements as inputs, and the manipulated variables as outputs. One application of the state space formulation is in combination with the process model to obtain a closed loop model. This can for example be used to check the steady-state solution and see whether integral action is obtained or not

Potential of interdigitated back contact silicon heterojunction solar cells for liquid phase crystallized silicon on glass with efficiency above 14

Liquid phase crystallization of silicon LPC Si on glass is a promising method to produce high quality multi crystalline Si films with macroscopic grains. In this study, we report on recent improvements of our interdigitated back contact silicon heterojunction contact system IBC SHJ , which enabled open circuit voltages as high as 661 mV and efficiencies up to 14.2 using a 13 m thin n type LPC Si absorbers on glass. The influence of the BSF width on the cell performance is investigated both experimentally and numerically. We combine 1D optical simulations using GenPro4 and 2D electrical simulations using Sentaurus TCAD to determine the optical and electrical loss mechanisms in order to estimate the potential of our current LPC Si absorbers. The simulations reveal an effective minority carrier diffusion length of 26 m and further demonstrate that a doping concentration of 4 1016 cm 3 and a back surface field width of 60 m are optimum values to further increase cell efficiencie

Family financial management: a real world perspective

The purpose of this study is to examine techniques used by families in the day-to-day management of their finances. The purpose is accomplished by analysis of data gathered through a series of in-depth interviews with the family money manager in seven different families. Each family was interviewed for a minimum of four hours, to examine what the family actually does and their reported explanation of why they do it. The families are all white, in first marriages, with children living at home. The family financial managers have a bachelor\u27s degree or less, and both spouses are employed at least part-time. Family income ranges from 40,000 to 60,000 annually;Several themes emerge from the data. These themes, in turn, are developed into a proposed financial management process. The proposed model, a grounded theory, suggests that families have a process for managing their money and that it focuses on the ideas of safety, control, comfort, and routine, with an overall goal of the family\u27s financial viability. The specific activities, largely mental, seen in the model are a result of a decision process that is shaped by several motivating factors including cash flow, the near future, feelings and values, experience, and situational knowledge. Respondents all said their goals are to live life to the max. and to be able to pay our bills. Although long-term planning, saving, and net worth appear to be of little or no concern, all respondents are home owners, have retirement programs (some minimal), and are protected from at least some catastrophic occurrence by health, property, and liability insurance;The study suggests five areas that have implications for the development and teaching of financial management practices: (1) motivators and how they influence the entire process; (2) tools and the need for a variety; (3) teaching and how formal educational efforts must expand on the motivational forces at work and include a variety of methods; (4) timing, including the short-term focus of the manager\u27s planning horizon and how life experiences impact financial decisions; and (5) the use of the mass media outlets to educate regarding family financial management

Behavioral Response of Amano Shrimp with a Predatory Stimulus

Amano Shrimp Evasion in Response to Predatory Stimulus This study observed the physical behavior of the crustacean Caridina multidentata, more commonly known as amano shrimp, and their response when introduced to a predation-like stimulus. This research sought to understand how amano shrimp are affected by the presence of fish and possible predation. This research carries significance as it could indicate whether the shrimp are affected by the water they’re in, and if that affects their capabilities to carry out their main commercial purpose. This study specifically looks at the amano shrimp and its ability to evade predation when exposed to a stimulus similar to that of a fish\u27s suction to obtain food. When amano shrimp are attacked by fish, the fish sucks water in rapidly to bring the shrimp into its mouth. The shrimp avoids the predation primarily through the use of their entire abdomen to push itself away from the suction. This motion is conducted with the use of leg-like extensions called pleopods and a uropod. Our research suggests there is a significant difference in evasion response when exposed to a predation stimulus while in fish contaminated water as opposed to clean water. The shrimp display a quicker response in fish contaminated water, and seem to be more cautious, as they display the response from further away