Experimental validation for chatter stability prediction

This research focused on the experimental validation for chatter stability prediction. An optimum machining was aimed to maximize the material removal rate, whilst maintaining a sufficient stability margin to assure the surface quality. High material removal rate in machining produced self-excited vibration or chatter of the cutting tool and the workpiece. This resulted in a poor surface finish and dimensional accuracy, chipping of the cutter teeth, and also may damage the workpiece as well as machining tool. Frequency response function of a single degree freedom flexural was measured and the cutting stiffness of tools were determined in order to be used in predicting chatter stability using semi discretization method. The aluminium 7075 specimens were used in the milling cutting experiment to validate the chatter stability diagram of mill uniform and variable cutters, where a set of spindle speed and depth of cut had tested. The vibration conditions of machining were identified by analysing the vibration signals and FFT spectrum whether it was stable or in a chatter condition. There are good agreement between predicted stability and cutting experiment for the down-milling operation using uniform 4 flute cutting tool. Stable conditions were shown outside the boundary of chatter region. The optimized cutting tool was predicted to suppress chatter. Machining experiment tests showed there were no chatter vibration conditions during machining process until 1.5 mm depth of cut. According to the results of machining experiment, it was proven that the variable tool had more capability to machining without producing chatter vibration as compared to the regular tool

Effect of femoral head size, subject weight and activity level on acetabular cement mantle stress following total hip arthroplasty

In cases where cemented components are used in total hip arthroplasty, damage or disruption of the cement mantle can lead to aseptic loosening and joint failure. Currently, the relationship between subject activity level, obesity and prosthetic femoral head size and the risk of aseptic loosening of the acetabular component in cemented THA is not well understood. This study aims to provide an insight into this. Finite element models, validated with experimental data, were developed to investigate stresses in the acetabular cement mantle and pelvic bone resulting from the use of three prosthetic femoral head sizes, during a variety of daily activities and one high impact activity (stumbling) for a range of subject body weights. We found that stresses in the superior quadrants of the cortical bone‐cement interface increased with prosthetic head size, patient weight and activity level. In stumbling, average von Mises stresses (22.4 MPa) exceeded the bone cement yield strength for an obese subject (143 kg) indicating that the cement mantle would fail. Our results support the view that obesity and activity level are potential risk factors for aseptic loosening of the acetabular component and provide insight into the increased risk of joint failure associated with larger prosthetic femoral heads

Unraveling the crosstalk between cell sheets of human adipose stem cells and keratinocytes

We have previously shown that 3D constructs of human adipose stem cells (hASCs) cell sheets led to the formation of de novo hair follicles and rete-ridges like structures. An up-regulation of keratinocyte growth factor (KGF) was also observed in the experimental condition in relation to the control groups. We hypothesized that the natural adhesive character of the cell sheets promoted the direct interaction between the host and the transplanted cells1. In this sense, the present work aims at elucidating this communication between hASCs and human keratinocytes (hKC) and determining the extent of its mediation by KGF. In an in vitro scratch assays we showed that the secretome of hASCs in contact with hKC promotes cell migration and closure of the scrape. Moreover, when KGF-antibody was added diminished hKC migration was observed, suggesting that KGF might be one of the key cytokines involved in the interaction with hASCs. Furthermore, in order to assess the communication via gap junctions (GJ), a calcein-AM transfer assay was carried out in the presence/absence of a GJ inhibitor. The transference of the dye from hASCs to adjacent hKC, confirmed both by fluorescence microscopy and flow cytometry, showed that these cells also communicate via GJ. Moreover while hKCs expressed connexin (cx)43 and cx26, highly expressed at the wound margins, hASCs were only positive for cx43  as shown by immunocytochemistry and flow cytometry. Finally, the direct communication between transplanted hASCs cell sheets and hKC at the wound margins is being addressed in a human ex-vivo skin model with an artificial wound, to better mimic the previous in vivo conditions and confirm our hypothesis. So far we were able to demonstrate that hASCs and hKCs communicate directly through cx43 and indirectly via KGF secreted by hASCs, which promote KCs migration. (1)       Cerqueira, M. T.; Pirraco, R. P.; Santos, T. C.; Rodrigues, D. B.; Frias, A. M.; Martins, A. R.; Reis, R. L.; Marques, A. P.; Cerqueira   Pirraco, RP,  Santos, TC,  Frias, AM,  Martins, AR,  Reis, RL, Marques, AP, M. T. Biomacromolecules 2013, 14, 3997â 4008.    Portuguese Foundation for Science and Technology (FCT) for MTC (SFRH/BPD/96611/2013),RPP(SFRH/BPD/101886/2014)info:eu-repo/semantics/publishedVersio

Design of Product Service Systems at the Base of The Pyramid

Abstract in UndeterminedThe Base of the Pyramid (BoP) consists of about two-fifths of the world population. This population can be categorized as poor with income of less than 2 dollars per day. It is important to alleviate poverty. One of the promising approaches to tackle the wicked problem of poverty is business development combined with poverty alleviation. In this approach, integrated solutions are necessary in order to address the diverse issues in the BoP. These integrated solutions are in the form of product service systems (PSS) rather than the conventional product-oriented or service-oriented solutions. In this paper, we explore different issues that need to be addressed in the PSS design at the BoP. We have also explored strategies used in this PSS design. We have used a case study to explain these issues and strategies. In addition, we have identified salient characteristics of the PSS design at the BoP

Implementación de procedimientos operacionales estándares de sanitización en la Empresa Agropecuaria Popoyan Proyecto La Carreta

La presente investigación se realizó en la Empresa Agropecuaria Popoyán S. A., ubicada en la zona 11, ciudad de Guatemala, "Proyecto La Carretera", su principal objetivo es el desarrollo de nuevos productos tipo. Mediante el diagnostico se pudo observar las distintas ensalada con variedades de lechuga que se desarrollan mediante la técnica del triple lavado, para asegurar la inocuidad y calidad del producto, en donde innovando se estudió el empaque de las atmósferas modificadas con la inyección de gases inerte para mantener y asegurar la calidad del producto, y durante la investigación se llevo a definir las cantidades de tiempos de inyección, vacío y sellado para que sean los niveles óptimos de empaque. Se evaluaron los parámetros microbiológicos, turgencia y color se determinó la vida de anaquel, las variedades de lechuga utilizadas fueron: lechuga romana, escarola amarilla y morada, las cuales previamente clasificadas con una inspección física, se determinaron aptas para desarrollar la fase descrita anteriormente. Los Procedimientos Operacionales Estándares de Sanitización (POES), son un eslabón de la cadena para garantizar el producto. Este describe el qué hacer en cada operación, las cuales van desde prevención de la contaminación cruzada hasta vigilar la salud de los empleados, las responsabilidades en cada procedimiento, la verificación y las concentraciones de producto utilizadas en cada área. Todo esto para mantener un estándar en las áreas y que los colaboradores tengan presente el propósito de cada procedimiento. La piña es un producto que al ser cortada para consumo en fresco tiene una vida de anaquel de cuatro días, con la aplicación de preservantes se alarga la vida de 8 días. Se realizó una evaluación sensorial para medir el agrado del consumidor del producto con aplicación de que preservantes prefiere y según el análisis, el bisulfito de sodio es de mayor preferencia por encima de la mezcla de: sorbato de potasio, ácido cítrico y bisulfito de sodio. El último tratamiento fue tomado del manual de la Food and Agriculture Organization (FAO) para la conservación de productos, Al evaluar la vida de anaquel retiene los parámetros como pH y grados Brix, ya que al comparar con el testigo este sufre una elevación de los parámetros al día tres, el cual es el día clave para detener estos procesos, la boleta en la cual se le hizo un análisis sensorial al consumidor día a día, la detección de olor como fermento, sabor en la clasificación de dulce y no aceptable, la textura la turgencia del producto en el nivel de pérdida día a día. Obteniendo de esta forma la información necesaria para tomar las medidas correspondientes para cada producto. En la fase de Producción más limpia se hace una propuesta de mejora de instalaciones y plan de mejoras. Con la implementación de esta fase se tendría un ahorro mensual de 20 m³ de agua. El metro cúbico tiene un precio de Q 60,00, teniendo un ahorro equivalente a Q 1 200,00

Innovation Commercialisation: Processes, Tools and Implications

Innovation commercialisation is a new direction in the literature. The challenge in these commercialisation-related activities is that they must simultaneously take into account the processes of generating innovations, developing products and services based on these aforementioned processes and then forming a business model around the product-service system. We see innovation commercialisation as a process that aims to create and implement a feasible business model for an innovation-based product-service system in the surrounding business ecosystem. This view builds on the literature on business model innovation, where the business model is seen as a value-creating subsystem in a complex system of business models, that is, within the business ecosystem. In our chapter, we describe a process that is used in more than 40 innovation commercialisation projects. The process has been developed and modified to serve the different needs of various innovation development groups. The process is iterative and has been divided into two parts: (1) proof of relevance and (2) in-depth development. We highlight the targets in the distinct stages of the process, the specific challenges related to the stages, tools and processes to tackle these challenges and the best practices based on the cases we have been investigating. Finally, we conclude the lessons learned, bringing them together into managerial implications that show how to get the best results out of innovation commercialisation projects.Post-print / Final draf