Active force control of 3-RRR planar parallel manipulator

This paper presents a new and novel method to control a 3-RRR (revolute-revolute-revolute) planar parallel manipulator using an active force control (AFC) strategy. A traditional proportional-integral-derivative (PID) controller was first designed and developed to demonstrate the basic and stable response of the manipulator in performing trajectory tracking tasks. Later, the AFC section was incorporated into the control scheme in cascade form by adding it in series with the PID controller (PID+AFC), its primary aim of which is to improve the overall system dynamic performance particularly when the manipulator is subjected to different loading conditions. Results clearly illustrate the robustness and effectiveness of the proposed AFC-based scheme in rejecting the disturbances compared to the traditional PID controller

Solid Suspension in Rotary-Stirred and in Liquid-Jet Stirred Vessels

Experimental data are provided on the just-suspension conditions for two types of mechanically-stirred units, namely rotary-agitated vessels and liquid jet-stirred tanks. Results for the conventional rotary-stirred vessels (propellers and 4-blade 45°-pitch turbines) are presented in terms of the well-established just-suspension speed, Nje, based on the 1-2 seconds criterion. Data on the liquid-jet stirred tanks are presented as the minimum liquid jet velocity through the nozzle at the point of just suspension of particles, Uje, for a range of nozzle diameters (0.005m to 0.0127m) in five flat-bottom geometrically similar cylindrical vessels with diameter in the range 0.15m to 0.3m. Experimental data on Nje and Uje. are interpreted in terms of a new model developed in this work. The general model equation is based on a balance of the hydrodynamics and body forces acting on the particles at various states of suspension and on the energy requirements for particle suspension. The form of the final equation depends on the geometrical configuration and on the source of agitation. Two equations are developed in this work: one for Nje, and the other for Uje. These are as follows: For propellers and turbines with D/T < 0.5 and: Predictions of the effect on Nje and Uje of the various physical and geometrical parameters are in reasonable agreement with corresponding experimental data obtained in this work and those reported in the literature, with the exception of the effect of particle diameter. Limited experimental observations suggest that the effect of particle diameter on just-suspension state can not be described by a single expression over the whole range of dp, as predicted by the model equations. Data obtained in this work with rotary agitation indicate that a downward-pumping propeller with D/T < 0.5 is the most energy efficient impeller of all the agitators examined. A comparison of the propeller- and jet-stirred vessels suggests that at just-suspension conditions, the power input into a propeller is about the same as the power input into a liquid-jet stirred unit operating under otherwise identical conditions, and provided that the ratio of nozzle diameter to vessel diameter is in the range 1/20–1/25

Linking Market Orientation To Strategy Through Segmentation Complexity

Relying on the cultural view of market orientation, we introduce segmentation complexity as a key mediator between market orientation (i.e., customer orientation and competitor orientation) and the strategies of differentiation, cost leadership, and innovation.&nbsp; Customer orientation is positively related to segmentation complexity, differentiation, and innovation, and negatively to cost leadership.&nbsp; Competitor orientation is positively related to all of these strategies.&nbsp; The indirect effects of both customer and competitor orientation are mediated through segmentation complexity, which is positively related to differentiation and innovation, and negatively to cost leadership

Motives For Purchasing Artwork, Collectibles And Antiques

Art is disaggregated into tangible and intangible offerings. Intangible art is one-time experiences of aesthetical and nostalgic products with no post-consumption exchange value. Tangible art preserves post-consumption exchange value. While psychographics of the consumers of intangible art are well-established, consumers of tangible art are under-researched. This research identifies and measures 16 different motives that underlie the purchase of artwork, collectibles and antiques. Heavy-consumers are found to score significantly higher than light-consumers on 8 of these motives: expected price fairness (economic); social acceptability and group identification (normative); aesthetics, pleasure and immersion (hedonic); culture (intellectual); and harmony. Findings are discussed and implications and limitations are also included

An exploratory investigation of the effects of co-production and co-consumption on the characteristics and adoption of service innovations: the customer's perspective.

Customers play an active role throughout the marketing process. This dissertation concerns itself with customer's co-creation of value for self (co-production) and for other customers (co-consumption) during service production and delivery. With the servuction system as its overarching framework, this study explains how changes in the customer's perceived co-production and co-consumption, caused by a service innovation, influence her perceptions of service innovation characteristics and modify her adoption behavior. It draws on a multidisciplinary body of knowledge and develops a conceptual framework and a set of substantive propositions. The empirical research was contextualized in three services: self check-out at grocery stores, Build-A-Bear stores, and meal assembly centers. It focused on members of Generations X and Y who were familiar with these services. The qualitative investigations and pilot study helped adapt the extant scales and construct new scales. In line with prior works, the focal service encounters were simulated through a series of consumption scenarios. The exploratory factor analysis in the pilot study and the confirmatory factor analysis in the main study indicated that the instruments were culturally informed, internally reliable, and construct-wise valid. The results indicate that co-production and co-consumption play important roles in explaining innovation characteristics and adoption decisions. More specifically, the focal customer's co-production of the service for self (CPS), other customers' co-production of the service for the focal customer (OCP), the number and the nature of other customers (crowding and homophily) can help to explain the focal customer's evaluation of service innovation characteristics as well as her adoption decision. The focal customer's disposition to participate (DTP) and its interaction with CPS are also useful explanatory constructs. Focal customer's co-production of the service for other customers (CPO) and its interaction with DTP emerged as non-significant. In comparing the high- and low-DTP groups, it was found that the former was more convenience-prone in two service contexts, and the latter in the third context

Determinants of medical tourism destination selection process

Even though American health care providers have incessantly raised their prices, medical insurers have managed to achieve (greater) profitability covering fewer services for a smaller number of clientele every year. Against this backdrop, there has been a sharp increase in the number of people seeking health care in foreign countries. Using prospect theory, this study finds medical tourism consideration to be driven by domestic medical costs, patient privacy concerns, medical restrictions, and foreign destination desirability. The latter is in turn influenced by tourist attractions and service quality assurance in addition to domestic medical costs. The findings and their implications and limitations are also discussed

Influence of hybridization on tensile behaviors of non-absorbable braided polymeric sutures

This paper aims to investigate the effects of fiber hybridization technique on the mechanical behaviors of non-absorbable braided composite sutures. Fifteen types of hybrid braided sutures (HBSs) made of polyester (PET), polypropylene (PP), and polyamide 6 (PA6) are produced and tested to measure ultimate tensile strength (UTS), maximum strain, elastic modulus, and breaking toughness. Based on the results, it is observed that the suture material plays a significant role in the tensile and mechanical performance of HBSs, and they can be tailored through the different combinations of yarns according to the required mechanical properties. Experiments exhibit occurrence positive hybrid effect in both maximum strain and elastic modulus, and negative hybrid effect in UTS. The optimal tensile performance is associated with the hybrid structure comprising 75% PA6-12.5% PET-12.5% PP. This means the ternary structure with higher PA6 content along with PP and PET, demonstrates a synergistic effect. Thus, such a ternary composite structure is very promising for the design of novel non-absorbable sutures. Due to the absence of similar results in the specialized literature, this paper is likely to advance the state-of-the-art composite non-absorbable sutures and contribute to a better understanding of the hybridization concept for optimizing composite material systems

3D printing on-water sports boards with bio-inspired core designs

Modeling and analyzing the sports equipment for injury prevention, reduction in cost, and performance enhancement have gained considerable attention in the sports engineering community. In this regard, the structure study of on-water sports board (surfboard, kiteboard, and skimboard) is vital due to its close relation with environmental and human health as well as performance and safety of the board. The aim of this paper is to advance the on-water sports board through various bio-inspired core structure designs such as honeycomb, spiderweb, pinecone, and carbon atom configuration fabricated by three-dimensional (3D) printing technology. Fused deposition modeling was employed to fabricate complex structures from polylactic acid (PLA) materials. A 3D-printed sample board with a uniform honeycomb structure was designed, 3D printed, and tested under three-point bending conditions. A geometrically linear analytical method was developed for the honeycomb core structure using the energy method and considering the equivalent section for honeycombs. A geometrically non-linear finite element method based on the ABAQUS software was also employed to simulate the boards with various core designs. Experiments were conducted to verify the analytical and numerical results. After validation, various patterns were simulated, and it was found that bio-inspired functionally graded honeycomb structure had the best bending performance. Due to the absence of similar designs and results in the literature, this paper is expected to advance the state of the art of on-water sports boards and provide designers with structures that could enhance the performance of sports equipment

Patient-specific 3D-printed splint for mallet finger injury

Despite the frequency of mallet finger injuries, treatment options can often be costly, time-consuming, and ill-fitted. Three-dimensional (3D) printing allows for the production of highly customized and inexpensive splints, which suggests potential efficacy in the prescription of casts for musculoskeletal injuries. This study explores how the use of engineering concepts such as 3D printing and topology optimization (TO) can improve outcomes for patients. 3D printing enables the direct fabrication of the patient-specific complex shapes while utilizing finite element analysis and TO in the design of the splint allowed for the most efficient distribution of material to achieve mechanical requirements while reducing the amount of material used. The reduction in used material leads to significant improvements in weight reduction and heat dissipation, which would improve breathability and less sweating for the patient, greatly increasing comfort for the duration of their recovery