Design of non conventional Synchronous Reluctance machine

Synchronous reluctance (SyR) and Permanent magnet Synchronous Reluctance (PM-SyR) machines represent an answer to the growing emphasis on higher efficiency, higher torque density and overload capability of ac machines for variable-speed applications. Their high performance is particularly attractive in electric traction and industry applications. The SyR technology represents a convenient solution to obtain high efficiency machines at reduced cost and high reliability. The manufacturing costs are comparable to other existing technologies such as induction motors. Different SyR and PM-SyR machines with different ratings and applications were designed, for comparison with induction motors having equal frame. An accurate comparison between Induction motors, SyR and PM-SyR machines is reported, with reference to the IE4 and IE5 efficiency specifications that could become mandatory in the next years. Three studies are classified under the term ”Non-Conventional” machines: Line-Start SyR motor: is a special SyR machine designed for constant speed applications, line supplied. The rotor flux barriers are filled with aluminum, to obtain a squirrel cage that resembles the one of an induction motor. The manufacturing costs are comparable to those of the induction motor, and the efficiency is higher. Two prototypes were realized and tested. FSW-SyR: tooth-wound coils and fractional slot per pole combinations were investigated. They are of interest because they permit a simplification and higher degree of automatization of the manufacturing process. However, FSW-SyR machines are known for their high torque ripple, low specific torque and power factor. The number of slots per pole was optimized to maximize the torque density. Dealing with the torque ripple, a lumped parameters model was used together with optimization in SyRE. A design with minimized ripple was obtained, comparable to a distributed winding machine in this respect. This design was prototyped and tested. Mild Overlapped SyR: this study shows a new winding configuration applied to SyR and PM-SyR machines. The proposed case is in the direction to find a hybrid solution between distributed winding and tooth winding motors, that permits to reduce costs and improve performances. One limitation of this solution is that only number of pole pairs equal to five or higher are feasible, and this reduces the applicability of the solution to classical industry applications, where one to three pole pairs are normally used

On the Lipschitz Constant of Deep Networks and Double Descent

Existing bounds on the generalization error of deep networks assume some form of smooth or bounded dependence on the input variable, falling short of investigating the mechanisms controlling such factors in practice. In this work, we present an extensive experimental study of the empirical Lipschitz constant of deep networks undergoing double descent, and highlight non-monotonic trends strongly correlating with the test error. Building a connection between parameter-space and input-space gradients for SGD around a critical point, we isolate two important factors -- namely loss landscape curvature and distance of parameters from initialization -- respectively controlling optimization dynamics around a critical point and bounding model function complexity, even beyond the training data. Our study presents novels insights on implicit regularization via overparameterization, and effective model complexity for networks trained in practice

La coscienza è tempo. "Esperienza e giudizio": eredità e sfida dell'ultimo Husserl

Time and time consciousness have always been for Edmund Husserl a kind of torment, a stimulus, an enigma, an 'ultimate and true absolute', as he wrote in the Ideen. This paper aims to show that Husserl addressed this topic, after the Vorlesungen, especially in his last published book Erfahrung und Urteil, presenting a solution that introduces a possible new perspective on thought. The conceptual core of this solution is found in the complex and fascinating analysis of passive temporal synthesis. Consciousness, temporality and perception become the terms of multiple equations in their fundamental, mobile and unguaranteed basis, in a way that challenges the centuries-old concept of the central unity of the constant ego. In the middle of dark times, aware of his 'discoveries' of the 1930s such as pre-predictivity, Lebenswelt, anonymous and functioning intentionality, and always on behalf of the new rationalism, this also seems to be one of the most important final responses given by Husserl to Heidegger, as well as one of his most fruitful legacies and challenges to further thinking

La coscienza è tempo. "Esperienza e giudizio": eredità e sfida dell'ultimo Husserl

Time and time consciousness have always been for Edmund Husserl a kind of torment, a stimulus, an enigma, an 'ultimate and true absolute', as he wrote in the Ideen. This paper aims to show that Husserl addressed this topic, after the Vorlesungen, especially in his last published book Erfahrung und Urteil, presenting a solution that introduces a possible new perspective on thought. The conceptual core of this solution is found in the complex and fascinating analysis of passive temporal synthesis. Consciousness, temporality and perception become the terms of multiple equations in their fundamental, mobile and unguaranteed basis, in a way that challenges the centuries-old concept of the central unity of the constant ego. In the middle of dark times, aware of his 'discoveries' of the 1930s such as pre-predictivity, Lebenswelt, anonymous and functioning intentionality, and always on behalf of the new rationalism, this also seems to be one of the most important final responses given by Husserl to Heidegger, as well as one of his most fruitful legacies and challenges to further thinking

A new PM-assisted synchronous reluctance machine with a nonconventional fractional slot per pole combination

Fractional-slot concentrated-winding synchronous permanent magnet machines (PM) are appreciated for their simple construction and high torque density. Unfortunately, it is well known that such fractional slot / pole combinations kill the reluctance torque potential of salient interior PM rotor configurations. To date, this has hindered the application of fractional windings to machines of the Synchronous Reluctance and PM-assisted Synchronous Reluctance types. This paper proposes a new fractional slot PM-assisted Synchronous Reluctance machine with 24 slots and 10 rotor poles. The new machine is compared to a benchmark 10-pole PM-assisted machine having 90 slots and distributed windings and to another competitor with 12 slots concentrated windings. FEA results show that the new machine is comparable to the distributed windings version in terms of torque density and losses, and much easier to be manufactured

Hyperplane Arrangements of Trained ConvNets Are Biased

We investigate the geometric properties of the functions learned by trained ConvNets in the preactivation space of their convolutional layers, by performing an empirical study of hyperplane arrangements induced by a convolutional layer. We introduce statistics over the weights of a trained network to study local arrangements and relate them to the training dynamics. We observe that trained ConvNets show a significant statistical bias towards regular hyperplane configurations. Furthermore, we find that layers showing biased configurations are critical to validation performance for the architectures considered, trained on CIFAR10, CIFAR100 and ImageNet

Approximation of 2d and 3d models of chemotactic cell movement in vasculogenesis

Cell migration plays a central role in a wide variety of biological phenomena. In the case of chemotaxis, cells (or an organism) move in response to a chemical gradient. Chemotaxis underlies many events during embrio development and in the adult body. An understanding of chemotaxis is not only gained through laboratory experiments but also through the analysis of model systems, which often are much more amenable to experimental manipulation. This work is concerned with the relaxation schemes for the numerical approximation of a 2D and 3D model for cell movement driven by chemotaxis. More precisely, we consider models arising in the description of blood vessels formation and network formation starting from a random cell distribution

Deep Double Descent via Smooth Interpolation

The ability of overparameterized deep networks to interpolate noisy data, while at the same time showing good generalization performance, has been recently characterized in terms of the double descent curve for the test error. Common intuition from polynomial regression suggests that overparameterized networks are able to sharply interpolate noisy data, without considerably deviating from the ground-truth signal, thus preserving generalization ability. At present, a precise characterization of the relationship between interpolation and generalization for deep networks is missing. In this work, we quantify sharpness of fit of the training data interpolated by neural network functions, by studying the loss landscape w.r.t. to the input variable locally to each training point, over volumes around cleanly- and noisily-labelled training samples, as we systematically increase the number of model parameters and training epochs. Our findings show that loss sharpness in the input space follows both model- and epoch-wise double descent, with worse peaks observed around noisy labels. While small interpolating models sharply fit both clean and noisy data, large interpolating models express a smooth loss landscape, where noisy targets are predicted over large volumes around training data points, in contrast to existing intuition

Design of a line-start synchronous reluctance motor

The design of line-start Synchronous Reluctance machines is proposed, based on the state of the art of motors designed for closed loop, vector control. The guidelines for overcoming the dilemma between synchronization capability and steady state performance are given, with examples of good and bad design choices. The proposed solutions compared via finite element analysis with a competitor induction motor in terms of efficiency and power factor. The finite element calculations are finally validated via experiments on a laboratory prototyp