Efficient electrochemical model for lithium-ion cells

Lithium-ion batteries are used to store energy in electric vehicles. Physical models based on electro-chemistry accurately predict the cell dynamics, in particular the state of charge. However, these models are nonlinear partial differential equations coupled to algebraic equations, and they are computationally intensive. Furthermore, a variable solid-state diffusivity model is recommended for cells with a lithium ion phosphate positive electrode to provide more accuracy. This variable structure adds more complexities to the model. However, a low-order model is required to represent the lithium-ion cells' dynamics for real-time applications. In this paper, a simplification of the electrochemical equations with variable solid-state diffusivity that preserves the key cells' dynamics is derived. The simplified model is transformed into a numerically efficient fully dynamical form. It is proved that the simplified model is well-posed and can be approximated by a low-order finite-dimensional model. Simulations are very quick and show good agreement with experimental data

Applying infrared thermography and image analysis to dilute 2-phase particulate systems: hot particle curtains

Particle curtains occur in industrial drying and in solar particle receivers and are defined as a stream of particles falling a fixed distance through a gas or fluid phase. In industrial drying optimising heat and mass transfer between the cascading particles and the drying medium is essential for enhancing energy efficiency and reducing emissions. Modelling these devices via pragmatic process systems models and/or with computational fluid dynamics models can contribute to enhanced design and a better understanding of the fundamental processes that occur. Validation of curtain modelling is critical to building confidence in the resultant predictions, but unfortunately traditional methods such as discrete temperature measurement using probes are time consuming and can disturb the flow field. Infrared thermography is an image-based technique with the potential to alleviate some of these issues and to generate whole of field temperature data, well-suited to model validation. In this paper infrared thermographic images of hot particle curtains falling through still air are presented. Image analysis methods for adjusting and scaling images as well as detecting the curtain edges are also described. Experiments involving hot particle curtains (403k-413K) falling through a narrow slot (150×20-60 mm) in a room filled with still air (295K-300K) are presented. Curtain widths were varied by varying the slot width (20 mm and 60 mm) and a range of mass flow rates (0.04 kg/s-0.155 kg/s) and particle diameters (290 μm and 400 μm) were examined. Curtain shape, as defined by the edges of the curtains, was determined using methods adapted from image analysis. The 2D thermal images showed that the shapes of the curtains are strongly dependent on slot width or initial solids volume fraction, which has implications for maximising heat transfer in particle curtain processes

Lithium-Ion battery SOC estimation

Lithium-ion batteries are frequently used in Hybrid electric vehicles (HEVs), which are taking the place of gas-engine vehicles. An important but not measurable quantity in HEVs is the amount of charge remaining in the battery in a drive cycle. The remaining charge is normally identified by a variable called state of charge (SOC). A potential way of estimating the SOC is relating this variable with the state of a dynamical system. Afterwards, the SOC can be estimated through an observer design. As a precise model, electrochemical equations are chosen in this research to estimate the SOC. The first part of this thesis considers comparison studies of commonly-used finite-dimensional estimation methods for different distributed parameter systems (DPSs). In this part, the system is first approximated by a finite-dimensional representation; the observer dynamics is a copy of the finite-dimensional representation and a filtering gain obtained through observer design. The main outcome of these studies is comparing the performance of different observers in the state estimation of different types of DPSs after truncation. The studies are then expanded to investigate the effect of the truncated model by increasing the order of finite-dimensional approximation of the system numerically. The simulation results are also compared to the mathematical properties of the systems. A modified sliding mode observer is improved next to take care of the system's nonlinearity and compensate for the estimation error due to disturbances coming from an external input. It is proved that the modified SMO provides an exponential convergence of the estimation error in the existence of an external input. In most cases, the simulations results of the comparison studies indicate the improved performance of the modified SMO observer. Approximation and well-posedness of two general classes of nonlinear DPSs are studied next. The main concern of these studies is to produce a low-order model which converges to the original equation as the order of approximation increases. The available results in the literature are limited to specified classes of systems. These classes do not cover the lithium-ion cell model; however, the general forms presented here include the electrochemical equations as a specific version. In order to facilitate the electrochemical model for observer design, simplification of the model is considered in the next step. The original electrochemical equations are composed of both dynamical and constraint equations. They are simplified such that a fully dynamical representation can be derived. The fully dynamical representation is beneficial for real-time application since it does not require solving the constraint equation at every time iteration while solving the dynamical equations. Next, the electrochemical equations can be transformed into the general state space form studied in this thesis. Finally, an adaptive EKF observer is designed via the low-order model for SOC estimation. The electrochemical model employed here is a variable solid-state diffusivity model. Compared to other models, the variable solid-state diffusivity model is more accurate for cells with Lithium ion phosphate positive electrode, which are considered here, than others. The adaptive observer is constructed based on considering an adaptive model for the open circuit potential term in the electrochemical equations. The parameters of this model are identified simultaneously with the state estimation. Compared to the experimental data, simulation results show the efficiency of the designed observer in the existence of modeling inaccuracy

Modeling and Control of a Magnetic Drug Delivery System

Therapeutic operation risk has been reduced by the use of micro-robots, allowing highly invasive surgery to be replaced by low invasive surgery (LIS), which provides an effective tool even in previously inaccessible parts of the human body. LIS techniques help delivering drugs effectively via micro-carriers. The micro-carriers are divided into two groups: tethered devices, which are supported by internally supplied propulsion mechanism, and untethered devices. Remote actuation is the critical issue in micro-device navigation, especially through blood vessels. To achieve remote control within the cardiovascular system, magnetic propulsion offers an advantage over other proposed actuation methods. In the literature, most research has focused on micro-device structural design, while there is a lack of research into design and analysis of combined structure and control. As the main part, integrating the principle of electromagnetic induced force by feedback control design will lead to the desired automatic movement. An actuator configuration should thus first be designed to initiate the desired force. The design is basically defining the type and placement of a set of coils to achieve an operational goal. In this project, the magnetic actuation is initiated by a combination of four electromagnets and two sets of uniform coils. Preliminary studies on 2D navigation of a ferromagnetic particle are used to show the effect of actuator structure on controller performance. Accordingly, the performance of the four electromagnets combination is compared to the proposed augmented structure with uniform coils. The simulation results show the improved efficiency of the augmented structure. In more general cases, the arrangement and number of electromagnets are unknown and should be defined. An optimization method is suggested to find these variables when the working space is maximized. Finally, the problem of robust output regulation of the electromagnetic system driven by a linear exosystem, is also addressed in this project. The exosystem is assumed to be neutrally stable with unknown frequencies. The parallel connection of two controllers, a robust stabilizer and an internal model-based controller, is presented to eliminate the output error. In the latter one, an adaptation is used to tune the internal model frequencies such that a steady-state control is produced to maintain the output-zeroing condition. The robust regulation with a local domain of convergence is achieved for a special class of decomposable MIMO nonlinear minimum-phase system. The simulation results show the effectiveness and robustness of this method for the electromagnetic system when two different paths are considered

Preparation and Physicochemical Evaluation of Cochleate-based Carriers for Insulin

Introduction: Cochleates are  cylindrical lipid structures that are more stable against oxidation and temperature than liposomes.  Our research is formulation of  cochleates for oral delivery of insulin as a model protein drug. Protein drugs are softer from environmental degradation and poor oral absorption; therefore any carrier system for their oral delivery must have protection against enzymes and absorption  enhancing ability. Methods and Results: In this study, liposomes with different proportion of lipids (DPPC and DMPC) and cholesterol were prepared by film hydration method and converted to cochleates by hydrogel method with CaCl2 and MgCl2. Microscopically observation of structures was carried out by phase-contrast microscope and Scanning Electron Microscope (SEM). Physicochemical characteristics of these structures were evaluated by measuring size distribution  using with  laser light scattering technique, entrapment efficiency percentage, investigation of release profile, and stability of selected cochleates. HPLC method  was used for analytical evaluation of entrapped and released insulin.Best formulation of liposomes contains 70% of lipid and 30% of cholesterol. According to microscopic size distribution, cochleates with CaCl2 bridges were better. The size of vesicles was less than 6 µm. Insulin entrapment efficiency of cochleates with DPPC was more than DMPC type. Between 60-70% of encochleated insulin released after 2-4 hours in a buffer with pH 6.8. Conclusions:The results shows that cochleates can be suitable oral delivery systems for insulin

Implementation of P-Controller in Computational Fluid Dynamics (CFD) Simulation of a Pilot Scale Outlet Temperature Controlled Spray Dryer

[EN] Most of the CFD simulations of spray dryers reported in the literature utilizes a fixed air inlet temperature numerical framework. In this paper, a numerical framework was introduced to model spray drying as an outlet air temperature controlled process. A P-controller numerical framework was introduced which allows the inlet temperature to be automatically adjusted based on the required outlet temperature set point. This numerical framework was evaluated with a simulation of a two-stage pilot scale spray drying system at the Davis Dairy Plant (South Dakota State University) which is used for commercial contract spray drying operation.Afshar, S.; Jubaer, H.; Metzger, L.; Patel, H.; Selomulya, C.; Woo, MW. (2018). Implementation of P-Controller in Computational Fluid Dynamics (CFD) Simulation of a Pilot Scale Outlet Temperature Controlled Spray Dryer. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 155-162. https://doi.org/10.4995/IDS2018.2018.7536OCS15516

Proposed TART-RADS Classification for Testicular Ultrasound: Our Experience and Literature Review

Background: Testicular adrenal rest tumors (TARTs) are an important complication in patients with Congenital Adrenal Hyperplasia (CAH). Ultrasonography is the diagnostic modality of choice. In this study we examined the possibility of sonographic classification of TARTs in the Reporting and Data Systems (RADS) imaging format.Methods: 35 male patients with the diagnosis of congenital adrenal hyperplasia due to 21 hydroxylase deficiency were evaluated.Results: 19 patients had one or more sonographic findings of TARTs. No significant relation was found between 17 Hydroxyprogesterone (17 OH p), ACTH and androstenedione levels in patients with and without TARTs. Five sonographic patterns for testicular lesions were found. The five-stage classification of sonographic findings of TARTs is matched with histological classifications.Conclusion: This classification system will allow clinicians to perform more accurate approaches. In general, TARTS should be considered in male patients with CAH. Sonography is a good imaging modality for the diagnosis of TARTs. TART-RADS imaging of lesions will allow clinicians to develop more accurate and appropriate approache

Characterization of an engineered human purine nucleoside phosphorylase fused to an anti-her2/neu single chain Fv for use in ADEPT

Abstract Background Antibody Directed Enzyme Prodrug Therapy (ADEPT) can be used to generate cytotoxic agents at the tumor site. To date non-human enzymes have mainly been utilized in ADEPT. However, these non-human enzymes are immunogenic limiting the number of times that ADEPT can be administered. To overcome the problem of immunogenicity, a fully human enzyme, capable of converting a non-toxic prodrug to cytotoxic drug was developed and joined to a human tumor specific scFv yielding a fully human targeting agent. Methods A double mutant of human purine nucleoside phosphorylase (hDM) was developed which unlike the human enzyme can cleave adenosine-based prodrugs. For tumor-specific targeting, hDM was fused to the human anti-HER2/neu single chain Fv (scFv), C6 MH3B1. Enzymatic activity of hDM with its natural substrates and prodrugs was determined using spectrophotomeric approaches. A cell proliferation assay was used to assess the cytotoxicity generated following conversion of prodrug to drug as a result of enzymatic activity of hDM. Affinity of the targeting scFv, C6 MH3B1 fused to hDM to Her2/neu was confirmed using affinity chromatography, surface plasmon resonance, and flow-cytometry. Results In vitro hDM-C6 MH3B1 binds specifically to HER2/neu expressing tumor cells and localizes hDM to tumor cells, where the enzymatic activity of hDM-C6 MH3B1, but not the wild type enzyme, results in phosphorolysis of the prodrug, 2-fluoro-2'-deoxyadenosine to the cytotoxic drug 2-fluoroadenine (F-Ade) causing inhibition of tumor cell proliferation. Significantly, the toxic small drug diffuses through the cell membrane of HER2/neu expressing cells as well as cells that lack the expression of HER2/neu, causing a bystander effect. F-Ade is toxic to cells irrespective of their growth rate; therefore, both the slowly dividing tumor cells and the non-dividing neighboring stromal cells that support tumor growth should be killed. Analysis of potential novel MHCII binding peptides resulting from fusion of hDM to C6 MH3B1 and the two mutations in hDM, and of the structure of hDM compared to the wild-type enzyme suggests that hDM-C6 MH3B1 should exhibit minimal immunogenicity in humans. Conclusion hDM-C6 MH3B1 constitutes a novel human based protein that addresses some of the limitations of ADEPT that currently preclude its successful use in the clinic

Nanotechnology in Wound Healing; Semisolid Dosage Forms Containing Curcumin-Ampicillin Solid Lipid Nanoparticles, in-Vitro, Ex-Vivo and in-Vivo Characteristics

Purpose: Wound healing is a natural biologic process, but the duration of it may take too long. Trying to shorten this process is one of the challenges for scientists. Many technologies were applied to achieve this goal as well as nanotechnology. In this study semi solid formulations containing curcumin and ampicillin solid lipid nanoparticles (SLNs) were prepared to evaluate as burn wound healing agent. Methods: Curcumin as an anti-inflammatory and anti-bacterial agent and ampicillin as an antibiotic were applied. In-vitro and in-vivo evaluations were carried out. Particle size, loading efficiency, release profile, morphology and anti-bacterial efficacy of desired nanoparticles were evaluated at first. Then the remaining of the antibacterial effect in semi solid preparations was studied. Animal studies for both toxicology using rabbits and skin burn model using rats were designed. Pathology studies after applying of formulations was done too. Results: Desired nanoparticles were spherical in shape and particle size in range of 112-121 nm, with low zeta potential. For increasing stability of particles they were freeze dried using cryoprotectant. Lyophilized particles show no significant size enlargement. Results showed that both ointment and gel preparations have reasonable anti-bacterial effects, both of them cause increasing in the rate of wound healing in comparison with placebos and control groups and none of the formulations showed acute toxicity. Conclusion: It seems that using nanotechnology could shorten wound healing process to reduce treatment costs and increase compliance of patients