On the Analysis and Control of a Linear Synchronous Servomotor with a Flexible Load

Industry's growing need for higher productivity is placing new demands on mechanisms connected with electrical motors, because these can easily lead to vibration problems due to fast dynamics. Furthermore, the nonlinear effects caused by a motor frequently reduce servo stability, which diminishes the controller's ability to predict and maintain speed. Hence, the flexibility of a mechanism and its control has become an important area of research. The basic approach in control system engineering is to assume that the mechanism connected to a motor is rigid, so that vibrations in the tool mechanism, reel, gripper or any apparatus connected to the motor are not taken into account. This might reduce the ability of the machine system to carry out its assignment and shorten the lifetime of the equipment. Nonetheless, it is usually more important to know how the mechanism, or in other words the load on the motor, behaves. A nonlinear load control method for a permanent magnet linear synchronous motor is developed and implemented in the thesis. The purpose of the controller is to track a flexible load to the desired velocity reference as fast as possible and without awkward oscillations. The control method is based on an adaptive backstepping algorithm with its stability ensured by the Lyapunov stability theorem. As a reference controller for the backstepping method, a hybrid neural controller is introduced in which the linear motor itself is controlled by a conventional PI velocity controller and the vibration of the associated flexible mechanism is suppressed from an outer control loop using a compensation signal from a multilayer perceptron network. To avoid the local minimum problem entailed in neural networks, the initial weights are searched for offline by means of a differential evolution algorithm. The states of a mechanical system for controllers are estimated using the Kalman filter. The theoretical results obtained from the control design are validated with the lumped mass model for a mechanism. Generalization of the mechanism allows the methods derived here to be widely implemented in machine automation. The control algorithms are first designed in a specially introduced nonlinear simulation model and then implemented in the physical linear motor using a DSP (Digital Signal Processor) application. The measurements prove that both controllers are capable of suppressing vibration, but that the backstepping method is superior to others due to its accuracy of response and stability properties.

Elastic properties and secondary structure formation of single-stranded DNA at monovalent and divalent salt conditions

Single-stranded DNA (ssDNA) plays a major role in several biological processes. It is therefore of fundamental interest to understand how the elastic response and the formation of secondary structures are modulated by the interplay between base pairing and electrostatic interactions. Here we measure force-extension curves (FECs) of ssDNA molecules in optical tweezers set up over two orders of magnitude of monovalent and divalent salt conditions, and obtain its elastic parameters by fitting the FECs to semiflexible models of polymers. For both monovalent and divalent salts, we find that the electrostatic contribution to the persistence length is proportional to the Debye screening length, varying as the inverse of the square root of cation concentration. The intrinsic persistence length is equal to 0.7 nm for both types of salts, and the effectivity of divalent cations in screening electrostatic interactions appears to be 100-fold as compared with monovalent salt, in line with what has been recently reported for single-stranded RNA. Finally, we propose an analysis of the FECs using a model that accounts for the effective thickness of the filament at low salt condition and a simple phenomenological description that quantifies the formation of non-specific secondary structure at low forces.

Interactome analysis reveals that FAM161A, deficient in recessive retinitis pigmentosa, is a component of the Golgi-centrosomal network.

Defects in FAM161A, a protein of unknown function localized at the cilium of retinal photoreceptor cells, cause retinitis pigmentosa, a form of hereditary blindness. By using different fragments of this protein as baits to screen cDNA libraries of human and bovine retinas, we defined a yeast two-hybrid-based FAM161A interactome, identifying 53 bona fide partners. In addition to statistically significant enrichment in ciliary proteins, as expected, this interactome revealed a substantial bias towards proteins from the Golgi apparatus, the centrosome and the microtubule network. Validation of interaction with key partners by co-immunoprecipitation and proximity ligation assay confirmed that FAM161A is a member of the recently recognized Golgi-centrosomal interactome, a network of proteins interconnecting Golgi maintenance, intracellular transport and centrosome organization. Notable FAM161A interactors included AKAP9, FIP3, GOLGA3, KIFC3, KLC2, PDE4DIP, NIN and TRIP11. Furthermore, analysis of FAM161A localization during the cell cycle revealed that this protein followed the centrosome during all stages of mitosis, likely reflecting a specific compartmentalization related to its role at the ciliary basal body during the G0 phase. Altogether, these findings suggest that FAM161A's activities are probably not limited to ciliary tasks but also extend to more general cellular functions, highlighting possible novel mechanisms for the molecular pathology of retinal disease.

Imaging the time-integrated cerebral metabolic activity with subcellular resolution through nanometer-scale detection of biosynthetic products deriving from (13)C-glucose.

Glucose is the primary source of energy for the brain but also an important source of building blocks for proteins, lipids, and nucleic acids. Little is known about the use of glucose for biosynthesis in tissues at the cellular level. We demonstrate that local cerebral metabolic activity can be mapped in mouse brain tissue by quantitatively imaging the biosynthetic products deriving from [U-(13)C]glucose metabolism using a combination of in situ electron microscopy and secondary ion mass-spectroscopy (NanoSIMS). Images of the (13)C-label incorporated into cerebral ultrastructure with ca. 100nm resolution allowed us to determine the timescale on which the metabolic products of glucose are incorporated into different cells, their sub-compartments and organelles. These were mapped in astrocytes and neurons in the different layers of the motor cortex. We see evidence for high metabolic activity in neurons via the nucleus (13)C enrichment. We observe that in all the major cell compartments, such as e.g. nucleus and Golgi apparatus, neurons incorporate substantially higher concentrations of (13)C-label than astrocytes.

Governance mode vs. governance fit: Performance implications of make-or-ally choices for product innovation in the worldwide aircraft industry, 1942-2000

We examine the impact of governance mode and governance fit on performance in make-or-ally decisions. We argue that while horizontal collaboration and autonomous governance have direct and countervailing performance implications, the alignment of make-or-ally choices with the focal firm's resource endowment and the activity's resource requirements leads to better performance. Data on the aircraft industry show that relative to aircraft developed autonomously, collaborative aircraft exhibit greater sales but require longer time-to-market. However, governance fit increases unit sales and reduces time-to-market. We contribute to the alliance and economic organization literatures. (Copyright © 2013 John Wiley & Sons, Ltd.)

Study of the skin anatomy with high-frequency (22 MHz) ultrasonography and histological correlation

AbstractThe present essay is aimed at getting the radiologist familiar with the basic histological skin structure, allowing for a better correlation with sonographic findings. A high-frequency (22 MHz) ultrasonography apparatus was utilized in the present study. The histological analysis was performed after the skin specimens fixation with formalin, inclusion in paraffin blocks and subsequent staining with hematoxylin-eosin. The authors present a literature review showing the relationship between sonographic and histological findings in normal cutaneous tissue, and discuss the technique for a better performance of the sonographic scan. High-frequency ultrasonography is an excellent tool for the diagnosis of different skin conditions. However, as this method is operator-dependent, it is crucial to understand the normal skin structure as well as the correlation between histological and sonographic findings.

Dominant-Negative Effects of Adult-Onset Huntingtin Mutations Alter the Division of Human Embryonic Stem Cells-Derived Neural Cells.

Mutations of the huntingtin protein (HTT) gene underlie both adult-onset and juvenile forms of Huntington's disease (HD). HTT modulates mitotic spindle orientation and cell fate in mouse cortical progenitors from the ventricular zone. Using human embryonic stem cells (hESC) characterized as carrying mutations associated with adult-onset disease during pre-implantation genetic diagnosis, we investigated the influence of human HTT and of an adult-onset HD mutation on mitotic spindle orientation in human neural stem cells (NSCs) derived from hESCs. The RNAi-mediated silencing of both HTT alleles in neural stem cells derived from hESCs disrupted spindle orientation and led to the mislocalization of dynein, the p150Glued subunit of dynactin and the large nuclear mitotic apparatus (NuMA) protein. We also investigated the effect of the adult-onset HD mutation on the role of HTT during spindle orientation in NSCs derived from HD-hESCs. By combining SNP-targeting allele-specific silencing and gain-of-function approaches, we showed that a 46-glutamine expansion in human HTT was sufficient for a dominant-negative effect on spindle orientation and changes in the distribution within the spindle pole and the cell cortex of dynein, p150Glued and NuMA in neural cells. Thus, neural derivatives of disease-specific human pluripotent stem cells constitute a relevant biological resource for exploring the impact of adult-onset HD mutations of the HTT gene on the division of neural progenitors, with potential applications in HD drug discovery targeting HTT-dynein-p150Glued complex interactions.

Vegetative and reproductive morphology of Kallymenia patens (Kallymeniaceae, Rhodophyta) in the Mediterranean Sea

Reproductive morphology of the Mediterranean red alga Kallymenia patens is described for the first time, confirming its position in the genus. K. patens is characterized by a non-procarpic female reproductive apparatus, carpogonial branch systems consisting of supporting cells bearing both three-celled carpogonial branches and subsidiary cells that lack a hypogynous cell and carpogonium; fusion cells develop numerous connecting filaments, and tetrasporangia are scattered over the thallus and are probably cruciately divided. Old fertile spathulate specimens of K. patens are morphologically similar to K. spathulata, but they can be distinguished by the length of spathulated proliferations (up to 0.6 cm and 6 cm, respectively), the length of inner cortical cells (up to 70 and 30 μm, respectively), and the gonimoblast location (in proliferations from the perennial part of the blade and over all the thallus surface, respectively)

Technological solution for the automatic replacement of the catalytic filaments in HWCVD

The degradation of the catalytic filaments is the main factor limiting the industrial implementation of the hot wire chemical vapor deposition (HWCVD) technique. Up to now, no solution has been found to protect the catalytic filaments used in HWCVD without compromising their catalytic activity. Probably, the definitive solution relies on the automatic replacement of the catalytic filaments. In this work, the results of the validation tests of a new apparatus for the automatic replacement of the catalytic filaments are reported. The functionalities of the different parts have been validated using a 0.2 mm diameter tungsten filament under uc-Si:H deposition conditions.

Electrochemical Characterisation of Filter Media Properties and Their Exploitation in Enhanced Filtration

Streaming potential measurements for the surface charge characterisation of different filter media types and materials were used. The equipment was developed further so that measurements could be taken along the surfaces, and so that tubular membranes could also be measured. The streaming potential proved to be a very useful tool in the charge analysis of both clean and fouled filter media. Adsorption and fouling could be studied, as could flux, as functions of time. A module to determine the membrane potential was also constructed. The results collected from the experiments conducted with these devices were used in the study of the theory of streaming potential as an electrokinetic phenomenon. Several correction factors, which are derived to take into account the surface conductance and the electrokinetic flow in very narrow capillaries, were tested in practice. The surface materials were studied using FTIR and the results compared with those from the streaming potentials. FTIR analysis was also found to be a useful tool in the characterisation of filters, as well as in the fouling studies. Upon examination of the recorded spectra from different depths in a sample it was possible to determine the adsorption sites. The influence of an external electric field on the cross flow microflltration of a binary protein system was investigated using a membrane electroflltration apparatus. The results showed that a significant improvement could be achieved in membrane filtration by using the measured electrochemical properties to help adjust the process conditions.

Characterization of Microparticle Retention Systems with Retention Process Analyzer

In the literature survey retention mechanisms, factors effecting retention and microparticles were studied. Also commercial microparticle retention systems and means to measure retention were studied. Optical retention measurement with RPA and Lasentec FBRM was studied. The experimental part contains study of different cationic polyacrylamides, anionic silica, bentonite and new generation micropolymer. In these studies the dosage, dosing order and dosing history were changing factors. The experimental work was done with RPA-apparatus with which, the retention process can be followed in real time. In testing was found that silica yielded better retention, when dosed nontraditionally before the polymer. Also silica was very dependant on the polymer dosage. With bentonite good colloidal retention was achieved with relatively low doses. Unlike silica bentonite was not dependant on polymer dosage. The relation of bentonite and polymer dosage is more defining when high retention is wanted. With 3-component systems using bentonite very high retention was achieved. With silica no improvement in retention was found in 3-component systems compared to dual component systems.

Fouling management and retention in nanofiltration of integrated paper mill effluents

Nanofiltration performance was studied with effluents from the pulp and paper industry and with model substances. The effect of filtration conditions and membrane properties on nanofiltration flux, retention, and fouling was investigated. Generally, the aim was to determine the parameters that influence nanofiltration efficiency and study how to carry out nanofiltration without fouling by controlling these parameters. The retentions of the nanofiltration membranes studied were considerably higher than those of tight ultrafiltration membranes, and the permeate fluxes obtained were approximately the same as those of tight ultrafiltration membranes. Generally, about 80% retentions of total carbon and conductivity were obtained during the nanofiltration experiments. Depending on the membrane and the filtration conditions, the retentions of monovalent ions (chloride) were between 80 and 95% in the nanofiltrations. An increase in pH improved retentions considerably and also the flux to some degree. An increase in pressure improved retention, whereas an increase in temperature decreased retention if the membrane retained the solute by the solution diffusion mechanism. In this study, more open membranes fouled more than tighter membranes due to higher concentration polarization and plugging of the membrane material. More irreversible fouling was measured for hydrophobic membranes. Electrostatic repulsion between the membrane and the components in the solution reduced fouling but did not completely prevent it with the hydrophobic membranes. Nanofiltration could be carried out without fouling, at least with the laboratory scale apparatus used here when the flux was below the critical flux. Model substances had a strong form of the critical flux, but the effluents had only a weak form of the critical flux. With the effluents, some fouling always occurred immediately when the filtration was started. However, if the flux was below the critical flux, further fouling was not observed. The flow velocity and pH were probably the most important parameters, along with the membrane properties, that influenced the critical flux. Precleaning of the membranes had only a small effect on the critical flux and retentions, but it improved the permeability of the membranes significantly.

Swarm Intelligent Selection and Optimization of Machining System Parameters for Microchannel Fabrication in Medical Devices

Current technology trends in medical device industry calls for fabrication of massive arrays of microfeatures such as microchannels on to nonsilicon material substrates with high accuracy, superior precision, and high throughput. Microchannels are typical features used in medical devices for medication dosing into the human body, analyzing DNA arrays or cell cultures. In this study, the capabilities of machining systems for micro-end milling have been evaluated by conducting experiments, regression modeling, and response surface methodology. In machining experiments by using micromilling, arrays of microchannels are fabricated on aluminium and titanium plates, and the feature size and accuracy (width and depth) and surface roughness are measured. Multicriteria decision making for material and process parameters selection for desired accuracy is investigated by using particle swarm optimization (PSO) method, which is an evolutionary computation method inspired by genetic algorithms (GA). Appropriate regression models are utilized within the PSO and optimum selection of micromilling parameters; microchannel feature accuracy and surface roughness are performed. An analysis for optimal micromachining parameters in decision variable space is also conducted. This study demonstrates the advantages of evolutionary computing algorithms in micromilling decision making and process optimization investigations and can be expanded to other applications

A convenient method for the determination of moisture in aromatic plants

A method is proposed for the determination of the moisture content of aromatic plants. This method is based on the co-distillation of the starting material in a modified Clevenger apparatus with four organic solvents (toluene, cyclohexane, dichloromethane and carbon tetrachloride). The results were compared with those obtained by oven drying at 105 ºC and steam distillation of the essential oil. The efficiencies of the methods were shown to be equivalent. The solvent distillation method was more practical, especially with respect to operating time (2 h).

Thylakoid Protein Phosphorylation in Regulation of Photosynthesis

Once the seed has germinated, the plant is forced to face all the environmental changes in its habitat. In order to survive, plants have evolved a number of different acclimation systems. The primary reaction behind plant growth and development is photosynthesis. Photosynthesis captures solar energy and converts it into chemical form. Photosynthesis in turn functions under the control of environmental cues, but is also affected by the growth, development, and metabolic state of a plant. The availability of solar energy fluctuates continuously, requiring non-stop adjustment of photosynthetic efficiency in order to maintain the balance between photosynthesis and the requirements and restrictions of plant metabolism. Tight regulation is required, not only to provide sufficient energy supply but also to prevent the damage caused by excess energy. The very first reaction of photosynthesis is splitting of water into the form of oxygen, hydrogen, and electrons. This most fundamental reaction of life is run by photosystem II (PSII), and the energy required for the reaction is collected by the light harvesting complex II (LHCII). Several proteins of the PSII-LHCII complex are reversibly phosphorylated according to the energy balance between photosynthesis and metabolism. Thylakoid protein phosphorylation has been under extensive investigation for over 30 years, yet the physiological role of phosphorylation remains elusive. Recently, the kinases behind the phosphorylation of PSII-LHCII proteins (STN7 and STN8) were identified and the knockout mutants of these kinases became available, providing powerful tools to elucidate the physiological role of PSII-LHCII phosphorylation. In my work I have used the stn7 and stn8 mutants in order to clarify the role of PSII-LHCII phosphorylation in regulation and protection of the photosynthetic machinery according to environmental cues. I show that STN7- dependent PSII-LHCII protein phosphorylation is required to balance the excitation energy distribution between PSII and PSI especially under low light intensities when the excitation energy transfer from LHC to PSII and PSI is efficient. This mechanism differs from traditional light quality-induced “state 1” – “state 2” transition and ensures fluent electron transfer from PSII to PSI under low light, yet having highest physiological relevance under fluctuating light intensity. STN8-dependent phosphorylation of PSII proteins, in turn, is required for fluent turn-over of photodamaged PSII complexes and has the highest importance upon prolonged exposure of the photosynthetic apparatus to excess light.