A framework for understanding and controlling batch cooling crystallization

In taking a different view of crystallization dynamics, this thesis reveals a new framework for addressing a prevalent process engineering challenge: control over the size of crystals produced by batch cooling crystallization. The thesis divides roughly into halves. In the first half, the crystal size control problem is introduced and the proposed framework for addressing this problem—termed the mass-count (MC) framework—is developed. This new framework is laid out along side the population balance (PB) framework, which is the prevailing framework for modeling crystallization dynamics and addressing the crystal size control problem. In putting the proposed and established frameworks side by side, the intent is not to say that one or the other is correct. Rather, the point is to show that they are different perspectives that facilitate different control approaches. The PB framework is built up from first principles; it is intellectually stimulating and mathematically complete, but it has a drawback for application: it does not directly enable feedback control. The MC framework, on the other hand, takes a less detailed view of crystallization dynamics and does not connect to crystallization theory as directly; it is also more conducive to application. In the second half of the thesis, the utility of the MC framework is put to the test. The framework is first applied to understand and model the crystallization dynamics for two widely different systems: darapskite salt crystallization from water and paracetamol crystallization from ethanol. Once the dynamics have been modeled, the framework is then used to develop feedback control schemes. These schemes are applied to both experimental systems and, in both cases, crystal size control is demonstrated.Ph.D

Sensitivity interpretations of the co-state trajectory for opimal control problems with state constraints

International audienceSensitivity relations in optimal control identify the costate trajectory and the Hamiltonian, evaluated along a minimizing trajectory, as gradients of the value function. Sensitivity relations for optimal control problems not involving state constraints and formulated in terms of controlled differential equation with smooth data follow easily from standard transversality conditions. In the presence of pathwise state constraints, if the data is nonsmooth or when the dynamic constraint takes the form of a differential inclusion, deriving the sensitivity relations is far from straightforward. We announce both 'full' and 'partial' sensitivity relations for differential inclusion problems with pathwise state constraints. The partial sensitivity relation identifies the costate with a partial subgradient of the value function with respect to the state, and the full sensitivity relation identifies the costate and the Hamiltonian with a subgradient of the value function with respect to time and state. The partial sensitivity relation is new for state constraint problems. The full sensitivity relation is valid under reduced hypotheses and for a stronger form of necessary conditions, as compared with earlier literature. It is shown for the first time also that the costate arc can be chosen to satisfy the two relations simultaneously. An example illustrates that a costate trajectory may be specially chosen to satisfy the sensitivity relations, and it is possible that some costate trajectories fail to do so

Annual Report of the University, 2007-2008, Volumes 1-6

Project Summary and Goals Historically, affirmative action policies have evolved from initial programs aimed at providing equal educational opportunities to all students, to the legitimacy of programs that are aimed at achieving diversity in higher education. In June 2003, a U.S. Supreme Court ruling on affirmative action pushed higher education across the threshold toward creating a new paradigm for diversity in the 21 51 century. The court clearly stale that affirmative action is still viable but that our institutions must reconsider our traditional concepts for building diversity in the next few decades. This shift in historical context of diversity in our society has led to an important objective: If a diverse student body is an essential factor in a quality higher education, then it is imperative that elementary, secondary and undergraduate schools fulfill their missions to successfully educate a diverse population. In NM, the success of graduate programs depends on the state\u27s P-12 schools, the community and institutions of higher education, and their shared task of educating all students. Further, when the lens in broadened to view the entire P - 20 educational pipeline, it becomes apparent that the loss of students from elementary school to high school is enormous, constricting the number of students who go on to college. Not only are these of concern to what is happening in terms of their academic education but as well in terms of the communities that are affected to make critical decision and become and stay involved in the political and policy world that affects them. Guiding Principles Engaging Latino Communities for Education New Mexico (ENLACE NM) is a statewide collaboration of gente who represent the voices of underrepresented children and families- people who have historically not had a say in policy initiatives that directly impact them and their communities. Therefore, they, and others from our community, are at the forefront of this initiative. We have developed this collaboration based on a process that empowers these communities to find their voice in the pursuit of social justice and educational access, equity and success

Recent Development of Hybrid Renewable Energy Systems

Abstract: The use of renewable energies continues to increase. However, the energy obtained from renewable resources is variable over time. The amount of energy produced from the renewable energy sources (RES) over time depends on the meteorological conditions of the region chosen, the season, the relief, etc. So, variable power and nonguaranteed energy produced by renewable sources implies intermittence of the grid. The key lies in supply sources integrated to a hybrid system (HS)