Varje dag stöter vi på förpackningar av olika slag. För många personer är öppnandet av dessa förpackningar ett svårt moment, då det krävs en viss grad av handstyrka för att klara av det. Nedsatt handstyrka kan bero på skador eller sjukdomar, som exempelvis Parkinsons sjukdom, fingerledsartros och ledgångsreumatism. Åldrandet har också en negativ påverkan på handens styrka och funktion. Ett exempel på svåröppnade förpackningar är de med skruvkork av plast. Många förpackningar för juice- och mjölkprodukter, samt PET-flaskor, har denna design. Det finns idag många hjälpmedel med syftet att öppna dessa förpackningar, men tester av befintliga hjälpmedel visar att de inte uppfyller användarnas krav på funktionalitet och användarvänlighet. Därför var målet med projektet att utveckla en funktionell produkt som passar så många korkstorlekar som möjligt, och även vara utformad så att den kommer åt korken på alla förpackningar. Som en del av produktutvecklingsprocessen intervjuades en grupp kvinnor, 67-85 år gamla, som alla upplever svårigheter med att öppna förpackningar med skruvkork. Deras åsikter och synpunkter var av stor betydelse för projektets resultat. Vidare var brainstorming, skisser, prototyptillverkning och CAD-modellering metoder som användes i projektet. CAD-modellen användes som underlag vid tillverkning av produkten. Projektet resulterade i en fungerande produkt tillverkad i aluminium, och passar alla korkstorlekar med diametern 25-41 mm, vilket omfattar alla korkar som finns på dagens förpackningar för juice- och mjölkprodukter, samt PET-flaskor. Produkten använder sig av en hävarm, som reducerar kraftåtgången med upp till 92 %, och kommer att underlätta öppnandet av förpackningar med skruvkorkar för personer med nedsatt handstyrka. / Every day we encounter various types of packaging. For many people, the opening of these packages is a difficult task, since it requires a certain degree of hand strength to succeed. Reduced hand strength can be a result of injuries or diseases such as Parkinson's disease, finger-joint osteoarthritis and rheumatoid arthritis. Aging also has a negative effect on hand strength and function. An example of packaging that is difficult to open, is the ones with a plastic screw cap. Many packages, containing juice and milk products, as well as PET bottles, have this design. Today there are many tools in order to open these packages, but tests of existing facilities indicate that they do not meet user demands for functionality and usability. Therefore, the aim of the project was to develop a functional product that fits so many cap sizes as possible, and also be designed so that it can access the cap on all packaging. As part of the product development process, a group of women, 67-85 years old, who all experience difficulties in opening packaging with screw caps, was interviewed. Their views and opinions were of great importance for the project. Furthermore, brainstorming, sketching, prototyping and CAD modeling were methods used in the project. The CAD model was used to manufacture the product. The project resulted in a functioning product made of aluminum, and fits all cap sizes with a diameter of 25-41 mm, which includes all caps in today's packaging for juice and milk products, as well as PET bottles. The product is using a lever, which reduces the power consumption by up to 92%, and will facilitate the opening of packaging with screw caps for people with reduced hand strength.

Industrial demands for higher productivity rates and more stringent part tolerances require faster production machines that can produce, assemble, or manipulate parts at higher speeds and with better accuracy than ever before. In a majority of production machines, such as machine tools, ball screw drives are used as the primary motion delivery mechanism due to their reasonably high accuracy, high mechanical stiffness, and low cost. This brings the motivation for the research in this thesis, which has been to develop new control techniques that can achieve high bandwidths near the structural frequencies of ball screw drives, and also compensate for various imperfections in their motion delivery, so that better tool positioning accuracy can be achieved at high speeds. A precision ball screw drive has been designed and built for this study. Detailed dynamic modeling and identification has been performed, considering rigid body dynamics, nonlinear friction, torque ripples, axial and torsional vibrations, lead errors, and elastic deformations. Adaptive Sliding Mode Controller (ASMC) is designed based on the rigid body dynamics and notch filters are used to attenuate the effect of structural resonances. Feedforward friction compensation is also added to improve the tracking accuracy at velocity reversals. A bandwidth of 223 Hz was achieved while controlling the rotational motion of the ball screw, leading to a servo error equivalent to 1.6 um of translational motion. The motor and mechanical torque ripples were also modeled and compensated in the control law. This improved the motion smoothness and accuracy, especially at low speeds and low control bandwidths. The performance improvement was also noticeable when higher speeds and control bandwidths were used. By adding on the torque ripple compensation, the rotational tracking accuracy was improved to 0.95 um while executing feed motions with 1 m/sec velocity and 1 g acceleration. As one of the main contributions in this thesis, the dynamics of the 1st axial mode (at 132 Hz) were actively compensated using ASMC, which resulted in a command tracking bandwidth of 208 Hz. The mode compensating ASMC (MC-ASMC) was also shown to improve the dynamic stiffness of the drive system, around the axial resonance, by injecting additional damping at this mode. After compensating for the lead errors as well, a translational tracking accuracy of 2.6 um was realized while executing 1 m/sec feed motions with 0.5 g acceleration transients. In terms of bandwidth, speed, and accuracy, these results surpass the performance of most ball screw driven machine tools by 4-5 times. As the second main contribution in this thesis, the elastic deformations (ED) of the ball screw drive were modeled and compensated using a robust strategy. The robustness originates from using the real-time feedback control signal to monitor the effect of any potential perturbations on the load side, such as mass variations or cutting forces, which can lead to additional elastic deformations. In experimental results, it is shown that this compensation scheme can accurately estimate and correct for the elastic deformation, even when there is 130% variation in the translating table mass. The ED compensation strategy has resulted in 4.1 um of translational accuracy while executing at 1 m/sec feed motion with 0.5 g acceleration transients, without using a linear encoder. This result is especially significant for low-cost CNC (Computer Numerically Controlled) machine tools that have only rotary encoders on their motors. Such machines can benefit from the significant accuracy improvement provided by this compensation scheme, without the need for an additional linear encoder.

Extrusion compounding addresses such problems as the non-homogeneity of the mixture and separation of fiber from the polymer during rotational molding, which consequently affect the mechanical and physical properties of the resulting composites. <p>Using triethoxyvinylsilane as chemical pre-treatment on flax fibers and linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) as polymer matrices, this study focused on the effects of flax fiber content (0%, 12.5% or 25%) and extrusion parameters such as barrel zone temperatures (75-110-120-130-140°C or 75-120-130-140-150°C) and screw speed (110 or 150 rpm) on the extrudate and composite properties (extrudate color, extrudate density, extrudate melt flow index, extrudate morphology, composite color, composite density, composite morphology, composite tensile strength and composite water absorption). <p>A mixture of chemically pre-treated flax fibers and powdered polyethylene matrices underwent extrusion compounding using a twin-screw extruder. The extrudates were then pelletized, ground, rotationally molded and cut into test specimens (composites). The mechanical and physical properties of both the extrudates and the composites from different treatments were then measured and compared. <p>Using multiple linear regression, models were generated to show quantitatively the significant effects of the process variables on the response variables. Finally, using response surface methodology and superposition surface methodology on the preceding data, the following optimum values for fiber content and extrusion parameters were determined: for LLDPE composites, fiber content = 6.25%, temperatures = 75-117.3-127.3-137.3-147.3°C, screw speed = 117.5 rpm; for HDPE composites, fiber content = 5.02%, temperatures = 75-118.1-128.1-138.1-148.1°C, screw speed = 125.56 rpm.

Ermüdungsanalyse mit Pro/Mechanica am Beispiel einer Förderschnecke

Growing energy demand in the world force people to investigate alternative energy sources. Unlike coal or other fossil fuels, renewable energy sources are promising for the future. Especially, seed oils are effectively used as energy sources such as fuel for diesel engines. The scope of this study is to develop an oil extraction machine specific to canola seed. In this study, seed oil extraction methods have been investigated and various alternatives for the extraction machine have been considered. For continuous operation, oil extraction with a screw press is evaluated as the most appropriate solution. Four different prototypes have been designed and manufactured. According to the results of testing of prototypes, they have been modified and gradually improved to increase oil extraction efficiency. The working principle of the selected screw press based on the rotation of a tapered screw shaft mounted inside a grooved vessel. The screw shaft is a single square-threaded power screw having an increasing root diameter from inlet to exit while the outside diameter of the screw shaft is 66 mm. Seeds are taken into the system at the point where the depth of the screw thread is maximum. Then they are pushed forward by the threads on the rotating screw shaft and pass through inside the vessel. So, the fed seeds are compressed as they move to the other side of the vessel. Recovered oil escapes from high pressure zone and drains back. The oil is drained out from the oil drainage holes that are machined on high pressure zone of the vessel. Besides, the cake is extruded at the end of the vessel and the screw shaft. The cake thickness is adjustable by the axial movement of the screw shaft. By adjusting the cake thickness, different pressures can be obtained. During the experiments, it is observed that four main features affect the oil recovery rate. These are the geometry of the grooves inside the vessel, the taper angle of the screw shaft, the operating temperature and the rotational speed. With the final prototype, an oil recovery efficiency of 62.5% has been achieved at 40 rpm with 15 kg/h seed capacity. Since the oil content of the seed is taken as 40%, oil recovery rate of the developed oil extraction machine is 3.75 kg/h. This efficiency is determined for a 0.8 mm cake thickness at 1.1 kW motor ower.

This Master’s Thesis seeks to explain the process of initiation undergone by Henry James’s characters. Characters are chosen for initiation into forbidden knowledge, and, like the Biblical Adam and Eve, are exiled as a result. Though initiation is erotic, it is not sexual, and society falsely perceives a sexually charged relationship between the initiator and the initiate, also called the complementary pair. The initiate faces exile and death because of his forbidden knowledge. He no longer has a place in his society, which leads to his social death and eventually physical death. James’s reader is initiated along with the characters, becoming a critical reader who no longer sees reading as a passive activity but brings his own judgment to the text. The Jamesian Reader does not face the same fate as the initiate, but he does change substantively as a result of his new perspective on the text.

The Victorian governess occupied a difficult position in Victorian society. Straddling the line between genteel and working-class femininity, the governess did not fit neatly into the rigid categories of gender and class according to which Victorian society organized itself. This troubling liminality caused the governess to become implicitly associated with another disturbing domestic presence caught between worlds: the Victorian literary ghost. Using Henry James’s novella The Turn of the Screw as a touchstone for each chapter, this thesis examines how the spectral mirrors the governess’s own spectrality – that is, her own discursive construction as a psychosocially unsettling force within the Victorian domestic sphere.

No description available.

The following work presents the design of a haptic training simulator for pedicle screw insertions in pediatric scoliosis surgery. In particular, the haptic simulator simulates the haptic sensations associated with probe channeling through the pedicle using the free-hand technique. The design includes 1 DOF custom haptic device, haptic model, and controller. The design is tested and evaluated for feasibility through a small pilot studying involving 5 expert surgeons. Significant agreement across expert surgeons was obtained regarding the feasibility and potential for the simulator to be a useful training tool.

The following work presents the design of a haptic training simulator for pedicle screw insertions in pediatric scoliosis surgery. In particular, the haptic simulator simulates the haptic sensations associated with probe channeling through the pedicle using the free-hand technique. The design includes 1 DOF custom haptic device, haptic model, and controller. The design is tested and evaluated for feasibility through a small pilot studying involving 5 expert surgeons. Significant agreement across expert surgeons was obtained regarding the feasibility and potential for the simulator to be a useful training tool.