Magnetic particle clutch controls servo system

Magnetic clutches provide alternative means of driving low-power rate or positioning servo systems. They may be used over wide variety of input speed ranges and weigh comparatively little. Power drain is good with overall motor/clutch efficiency greater than 50 percent, and gain of clutch is close to linear, following hysteresis curve of core and rotor material

Investigation into low power active electromagnetic damping for automotive applications

Automobile suspension systems carry out two important functions; road handling and passenger comfort. Hydraulic passive dampers are the most common system employed on vehicles, yet it is well known that passive suspension systems are less effective on lightweight vehicles. Modern damper technologies such as semi-active and active dampers, offer potential benefits when used in these vehicles. An active electromagnetic (e.m.) damper could offer these same benefits with lower power consumption and with less mechanical complexity than existing active suspension systems. This research investigates the effectiveness of e.m. passive and active damping on the performance of lightweight electric vehicles and develops a novel, fully integrated model of the e.m. damper in both passive and active modes. The proposed e.m. damper consisted of one or more cylindrical permanent magnets that travelled axially through one or more cylindrical solenoids. A magnet/solenoid damper system was modelled for both the passive and active modes. The magnets were modelled as a current carrying solenoid and from Maxwell's Laws the magnetic field was determined. For the passive damper, the magnetic field was used with Faraday's Law to determine the forces generated. In the case of the active damper the magnetic field and the current in the damper solenoid were used to calculate the magnetic force. Both a passive and active e.m. damper were modelled for a small, one degree of freedom experimental system. The active e.m. damper was modelled as a pure Skyhook damper. There was a good correlation between the modelled and experimental data for the magnet, the passive and the active Skyhook dampers. The passive damper model was scaled up as a two degree of freedom system using realistic values for a road legal lightweight electric vehicle and demonstrated that sufficient passive damping could be achieved for automotive uses, but at the price of excessive mass. For the scaled up active damper model, sufficient force could be achieved with a mass similar to a commercial hydraulic damper. The power consumption was less than 5 % of an equivalent active hydraulic suspension system. This demonstrated that the passive damper was currently impractical for lightweight electric vehicles, but the active electromagnetic damper was of sufficiently low weight and power consumption: had enough authority and offered sufficient passenger comfort benefits to include in future lightweight electric vehicle designs

Ozone Depletion and Global Warming

Abstract This thesis examines global warming and the possible contribution that ozone depletion provides to this warming. An examination is performed to determine the extent of any warming/cooling events within the Earth-atmosphere system. The change in energy corresponding to this warning of the Earth- atmosphere system is estimated as being equivilent to an increase of mean solar input of 0.22W/m2. This is compared to the predicted changes of solar input for the two most common global warming scenarios: greenhouse gases and solar irradiance variance; and for a less well explored scenario, snow-ice albedo change. Examination of ozone depletion data shows that an absence of ozone in the stratosphere produces an increase in UV-B radiation at the surface of the Earth. This increase in UV-B light has not previously been thourougly examined in any of the global warming scenarios. This is presented as a fourth scenario for global warming. An analytical three layer model of the Earth-atmosphere, based on an earlier two layer model, is developed. Using this model it is determined that greenhouse gases, solar irradiance, snow-ice albedo feedback and ozone depletion can cause warming of the Earth's atmosphere. After comparison with other models, a snow-ice albedo mechanism is incorporated into the three layer model. This produces an amplification effect of any warming that occurs. Compared to the observed increase of surface temperature between 1975-2000 of 0.55 K, the model using a snow-ice albedo feedback, produced an increase of temperature of 1.4 K for greenhouse gases, 0.294 K for a solar irradiance increase and 0.119 K caused by a decrease in the ozone layer. Of the greenhouse gas, solar irradiance and ozone depletion scenarios, ozone depletion demonstrates the most realistic relative changes with a cooling of the stratosphere and a warming of the troposphere and Earth's surface as has been observed. It is concluded that ozone depletion is likely for a reasonable part of observed global warming

Factores de diferenciación en la exportación de mangos frescos por los agricultores del distrito de Mojeque–Ancash al mercado Estadounidense-2017

El presente trabajo, tiene como finalidad determinar los factores de diferenciación en las exportaciones de mango fresco por parte de los agricultores del distrito de Mojeque-Ancash al mercado estadounidense, esto con la intención de ayudar a los agricultores a conocer sus limitaciones y conozcan la forma de cómo exportar correctamente y entorno a ello, los requerimientos del mercado internacional. Para el desarrollo de esta investigación, se utilizó información documental complementándola con la aplicación de la técnica de la encuesta, para lograr los objetivos propuestos. Siendo aplicado a 90 agricultores que cuentan con terrenos certificados por SENASA como óptimos para la exportación. Llegando a la conclusión que para el 52% de los encuestados, la calidad es una ventaja frente a sus competidores de otros países, el 99% de los agricultores cuenta con el Global Gap y la ficha de Inspección del SENASA, como los certificados de calidad para la producción del mango de exportación y el 100% de estos, considera como una ventaja competitiva a la ventana comercial. Mientras que el 99% de los productores lo exporta de manera indirecta, percibiendo cinco veces más en promedio, el intermediario que le da el paso al producto desde el Incoterms EXW hasta el FOB

The Implementation in VISSIM REALTIME of an Active Electromagnetic Damper Controller for Lightweight Electric Vehicles

The use of linear electromagnetic active damper units in the suspension system of a lightweight electric vehicle offers many advantages over conventional passive, semi-active and active hydraulic dampers. While full active hydraulic systems have been commercially available in automobiles for many years, the linear electromagnetic active damper offers a lower weight system with a much reduced power demand. However an active system requires the use of a controller to adjust the power output to the damper unit. This unit must process signal inputs and provide an output solution within a short time period, often 5 milliseconds or less. By using VISSIM REALTIME, a controller was built that controlled a scale linear electromagnetic damper using Karnopp’s Skyhook algorithm. This had to deal with issues such as accelerometer drift and signal to noise ratio. These required simple but fast techniques to provide useful information to the damper in a useful timeframe. This controller-damper combination proved effective in reducing the vibration experienced by the sprung mass and was more effective than an ideal passive damper at all frequencies tested by at least a factor of three

Entre lo formal y lo real: el discurso de los operadores de justicia en los protocolos a seguir con las víctimas de trata de personas en la ciudad de Lima

Esta tesis se resume a el accionar selectivo del sistema punitivo a las víctimas de Trata de Personas que resulta de los operativos de intervención y/o rescate en la ciudad de Lima. Los hallazgos son evidenciados a partir del análisis de las representaciones sociales de los operadores de justicia en la aplicación y uso de los protocolos de intervención. Se evidencia que las representaciones sociales creadas en los operadores de justicia son productos de una experiencia social. Tales representaciones tratan de responder a una víctima con complicaciones en las estructuras fiscalizadoras del delito a causa de una confusión de la tipificación legal desde el Protocolo de Palermo adoptado por el Perú sin una previa contextualización, a estereotipos culturales y socio – económicos, cómo también, a una deficiencia en los soportes y mecanismos institucionales de los diversos órganos del Estado que participan en la fiscalización del delito. Por lo tanto, las consecuencias negativas de estas representaciones son crear un determinado perfil de víctimas en el delito de Trata de Personas separando en dos grupos a las víctimas: “ideales” y “no ideales”, confusión en los operadores de justicia al momento de aplicar y/o usar los diferentes Protocolos, una victimización secundaria en las víctimas “no ideales” lo que produce una baja cultura de denuncia y desconfianza hacia las autoridades

Design of Multifunctional Materials: Chalcogenides and Chalcopyrites

There is a strong need for developing multifunctional materials to reduce the cost of applied material without compromising the performance of the detectors, devices and sensors. The materials design, processing, growth and fabrication of bulk and nanocrystals and fabrication into devices and sensors involve huge cost and resources including a multidisciplinary team of experts. Because of this reason, prediction of multifunctionality of materials before design and development should be evaluated. Chalcogenides and chalcopyrites are a very exciting class of materials for developing multifunctionality. Materials such as Gallium selenide GaSe and zinc selenide ZnSe have been proven to be excellent examples. GaSe is a layered material and very difficult to grow in large crystal. However, it's ternary and quaternary analogs such as thallium gallium selenide TlGaSe2, thallium gallium selenide sulfide TlGaSe2-xSs, thallium arsenic selenide Tl3AsSe3, silver gallium selenide AgGaGe3Se8, AgGaGe5Se12 and several others have shown great promise for multifunctionality. Several of these materials have shown good efficiency for frequency conversion (nonlinear optical NLO), electro-optic modulation, and acousto-optic tunable filters and imagers suitable for the visible, near-infrared wavelength, mid wave infrared (MWIR), long wave infrared (LWIR) and even up to Tera hertz wavelength (THW) regions. In addition, this class of materials have demonstrated low absorption coefficients and power handling capability in the systems. Also, these crystals do not require post growth annealing, show very large transparency range and fabricability

Low Size, Weight and Power Concept for Mid-Wave Infrared Optical Communication Transceivers Based on Quantum Cascade Lasers

The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept presented, realized and tested in the laboratory environment. Resilience to atmospheric impairments analyzed with simulated turbulence. Performance compared to typical telecom based Short Wavelength Infra-Red transceiver

Electromagnetic damper control strategies for light weight electric vehicles

An investigation is conducted into the performance of passive, semi-active and active electromagnetic dampers. Theoretical models are constructed of the dampers and these are included in two degree of freedom models of the suspension. The passive and semi-active electromagnetic dampers are significantly heavier than commercial hydraulic dampers. In the case of active electromagnetic damper, the reduction in passenger acceleration is 88 percent when compared to passive damper and 61 percent when compared to a semi-active damper. The power consumption is similar to a magnetorheological semi-active damper