Impes modeling of volumetric dry gas reservoirs with mobile water

As the importance of natural gas as a resource increases, the importance of volumetric dry gas reservoirs with mobile water as the dominant gas reservoir types will also increase. This research developed an efficient, user-friendly simulation program specifically designed to model two-phase flow of gas and water in these reservoirs. Since fluid compression and viscous forces are the dominant parameters that control fluid movement in a dry gas reservoir, we used the Implicit Pressure and Explicit Saturation (IMPES) formulation of flow equations in which neither gravity nor capillary pressure terms are pertinent. Therefore, the IMPES approach showed greater stability for all cases considered in this work. The developed simulator is a Visual Basic Application (VBA) code for which the users can obsereve the results in a pertinent Microsoft Excel file. This program allows users to study the depletion behavior of volumetric dry gas reservoirs with mobile water as efficiently and accurately as is now possible in more expensive commercially available reservoir simulators. The program was validated by comparing the results with a well-recognized commercial reservoir simulator (CMG). The results of a battery of tests of this simulator matched very well with results of the commercial reservoir simulator for all tested schemes including different simulation plans; reservoir, grid and fluid data; and well configurations. The observed applicability of the program suggests when dealing with volumetric dry gas reservoirs with mobile water there is no need to employ more expensive commercial reservoir simulators, as the program can reliably be used for any simulation scheme of this case. Furthermore, the program can later be applied in a more robust reservoir simulator as the part that handles dry gas cases

The effect of stroke on foot biomechanics; underlying mechanisms and the functional consequences

Although approximately one-third of stroke survivors suffer abnormal foot posture and this can influence mobility [1], there is very little objective information regarding the foot and ankle after stroke

The effect of stroke on foot kinematics and the functional consequences

Background Although approximately one-third of stroke survivors suffer abnormal foot posture and this can influence mobility, there is very little objective information regarding the foot and ankle after stroke. Objective As part of a programme of research examining foot and ankle biomechanics after stroke, we investigated multi-planar kinematics and the relationship with function. Methods In a single assessment session, static foot posture (Foot Posture Index); mobility limitations (Walking Handicap Scale) and multi-segment foot and ankle kinematics during stance phase of walking were measured in 20 mobile chronic stroke survivors and 15 sex and age-matched healthy volunteers. Results Compared to the healthy volunteers, the stroke survivors demonstrated consistently reduced range of motion across most segments and planes, increased pronation and reduced supination, disruption of the rocker and the timing of joint motion. Changes in pronation/supination were associated with limited walking ability. Conclusions This study provides evidence of structural and movement deficiencies in the intrinsic foot segments affected by stroke. These would not have been detectable using a single segment foot model. Data do not support common clinical practices that focus on correction of sagittal ankle deformity and assumed excessive foot supination. Some of these abnormalities were associated with limitation in functional ability. Biomechanical abnormalities of foot and ankle are modifiable and there is potential for clinical studies and future developments of interventions to help prevent or treat these abnormalities which may improve functional ability post stroke

Evaluation of in-shoe plantar pressure and shear during walking for diabetic foot ulcer prevention.

To investigate reliability and changes of in-shoe plantar pressure and shear during walking at three cadences with two insole designs. This was a precursor to the investigation of plantar loading in people with diabetes for potential foot ulcer prevention. A sensorised insole system, capable of measuring plantar pressure and shear at the heel, fifth metatarsal head (5MH), first metatarsal head (1MH) and hallux, was tested with ten healthy participants during level walking. Reliability was evaluated, using intra-class correlation coefficient (ICC), while varying the cadences and insole types. Percentage changes in pressure and shear relative to values obtained at self-selected cadence with a flat insole design were investigated. Mean±standard deviation of maximum pressure, medial-lateral and anterior-posterior shear of up to 380±24kPa, 46±2kPa and -71±4kPa, respectively, were measured. The ICC in ranges of 0.762-0.973, 0.758-0.987 and 0.800-0.980 were obtained for pressure, anterior-posterior and medial-lateral shear, respectively. Opposite anterior-posterior shear directions between 5MH and 1MH (stretching), and between 1MH and hallux (pinching) were observed for some participants. Increasing cadence increased pressure and anterior-posterior shear (by up to +77%) but reduced medial-lateral shear at the heel and hallux (by up to -34%). Slower cadence increased anterior-posterior shear (+114%) but decreased medial-lateral shear (-46%) at the hallux. The use of a flexible contoured insole resulted in pressure reduction at the heel and 5MH but an increase in anterior-posterior shear at the heel (+69%) and hallux (+75%). The insole system demonstrated good reliability and is comparable to reported pressure-only systems. Pressure measurements were sensitive to changes in cadence and insole designs in ways that were consistent with the literature. However, our plantar shear showed localised shear changes with cadences and insoles for the first time, as well as stretching and pinching effects on plantar tissue. This opens new possibilities to investigate plantar tissue viability, loading characteristics and orthotic designs aimed towards foot ulcer prevention

An anatomically-based masking protocol for the assessment of in-shoe plantar pressure measurement of the forefoot

Background The area beneath the metatarsal heads is a common location of foot pain, which is often associated with high plantar pressures. Current plantar pressure assessment protocols focus mainly on the gross area of the forefoot with minimal attention paid to specific areas such as the metatarsal heads. The aim of this study was to develop and assess a new anatomically-based masking protocol that is clinically relevant to measure forefoot plantar pressure during shod conditions based on the anatomical positions of the metatarsal heads. Methods Initially, we developed a masking protocol to measure forefoot plantar pressure during shod conditions based on the anatomical positions of the metatarsal heads. This new masking protocol divided the forefoot into three sub-areas (proximal, beneath, and distal to the metatarsal heads) as determined by the position of each metatarsal head. Following development of the new masking protocol, we compared the new protocol against a traditional protocol, which defines the forefoot as between 51 and 81% of the foot length. To compare the two masking protocols, we tested two experimental conditions: (i) a control condition (i.e. no metatarsal pad), and (ii) a metatarsal pad condition. We then compared plantar pressure differences between the two experimental conditions for the two masking protocols. Participants for this component of the study included 36 community dwelling older adults (mean age 75.6 years ±5.4) with a history of forefoot pain. Forefoot plantar pressure data were measured while walking using the pedar®-X in-shoe system. Peak pressure, maximum force and contact area at the time of peak pressure were determined and results were compared between the two masking protocols. Results The traditional masking protocol showed that the metatarsal pad significantly decreased peak pressure and increased contact area in the forefoot area (i.e. within the entire mask area), but maximum force was not significantly different between the two conditions. In contrast, the newly developed anatomically-based masking protocol indicated that the metatarsal pad decreased peak plantar pressures distal to and beneath the metatarsal heads by increasing force and contact area proximal to the metatarsal heads. Conclusions An anatomically-based masking protocol that is clinically relevant was developed to assess forefoot plantar pressure during shod conditions based on the anatomical positions of metatarsal heads. We propose that the new forefoot masking protocol will provide greater interpretability of forefoot plantar pressure data, which will aid clinicians and researchers for diagnostic, prognostic and therapeutic purposes

The influence of staff training and education on prosthetic and orthotic service quality : a scoping review

Background: Education and training in prosthetics and orthotics typically comply with International Society for Prosthetics and Orthotics standards based on three categories of prosthetic and orthotic professionals. Objective: This scoping study sought to describe the evidence base available to answer the question, How are prosthetic and orthotic services influenced by the training of staff providing them? Study design: Scoping review. Methods: A structured search of the peer-reviewed literature catalogued in major electronic databases yielded 3039 papers. Following review of title and abstract, 93 articles were considered relevant. Full-text review reduced this number to 25. Results: Only two articles were identified as providing direct evidence of the effects of training and education on service provision. While both suggested that there was an impact, it is difficult to see how the more specific conclusions of either could be generalised. The other 23 articles provide a useful background to a range of issues including the specification of competencies that training programmes should deliver (3 articles), descriptions of a range of training programmes and the effects of training and education on student knowledge and skills. Conclusion: Although it is considered axiomatic, the service quality is dependent on practitioner education and training. There is insufficient evidence to establish whether levels of training and education in prosthetics and orthotics have an effect on the quality of prosthetic and orthotic services. Clinical relevance: There is very little evidence about the effects of training and education of prosthetists and orthotists on service quality. While this is a somewhat negative finding, we feel that it is important to bring this to the attention of the prosthetics and orthotics community

Centre of pressure characteristics in normal, planus and cavus feet

Background The aim of this study was to compare centre of pressure (COP) characteristics between healthy adults with normal, planus or cavus feet who were allocated to groups based on reliable foot posture measurement techniques. Methods Ninety-two healthy adult participants (aged 18 to 45) were recruited and classified as either normal (n = 35), pes planus (n = 31) or pes cavus (n = 26) based on Foot Posture Index, Arch Index and normalised navicular height truncated measurements. Barefoot walking trials were conducted using an emed®-x 400 plantar pressure system (Novel GmbH, Munich, Germany). Average, maximum, minimum and range (difference between maximum and minimum) values were calculated for COP velocity and lateral-medial force index during loading response, midstance, terminal stance and pre-swing phases of stance. The COP excursion index was also calculated. One-way analyses of variance were used to compare the three foot posture groups. Results The cavus foot exhibited the slowest average and minimum COP velocity during terminal stance, but this pattern was reversed during pre-swing, when the cavus foot exhibited the fastest maximum COP velocity. The planus foot exhibited the smallest lateral medial force index range during terminal stance. There were no differences between the groups for COP excursion index. Conclusion These findings indicate that there are differences in COP characteristics between foot postures, which may represent different mechanisms for generating force to facilitate forward progression of the body during the propulsive phases of gait

The influence of standards and clinical guidelines on prosthetic and orthotic service quality : a scoping review

OBJECTIVES: Standards and guidelines are an integral part of prosthetic and orthotic service delivery in the developed world underpinned by an assumption that they lead to improved services. Implementing them has a cost, however, and that cost needs to be justified, particularly in resource-limited environments. This scoping review thus asks the question, "What is the evidence of the impact of standards and guidelines on service delivery outcomes in prosthetics and orthotics?" MATERIALS AND METHODS: A structured search of three electronic databases (Medline, Scopus and Web of Science) followed by manual searching of title, abstract and full text, yielded 29 articles. RESULTS: Four categories of papers were identified: Descriptions and Commentaries (17 papers), Guideline Development (7), Guideline Testing (2) and Standards implementation (3). No articles were explicitly designed to assess the impact of standards and guidelines on service delivery outcomes in prosthetics and orthotics. DISCUSSION AND CONCLUSION: Studies tended to be commentaries on or descriptions of guideline development, testing or implementation of standards. The literature is not sufficiently well developed to warrant the cost and effort of a systematic review. Future primary research should seek to demonstrate whether and how guidelines and standards improve the outcomes for people that require prostheses, orthoses and other assistive devices. Implications for Rehabilitation International Standards and Clinical Guidelines are now an integral part of clinical service provision in prosthetics and orthotics in the developed world. Complying with standards and guidelines has a cost and, particularly in resource-limited environments, it should be possible to justify this in terms of the resulting benefits. This scoping review concludes that there have been no previous studies designed to directly quantify the effects of implementing standards and guidelines on service delivery