Using Simulation Model to Reduce System Design Time and Cost

Introduction This paper presents the findings of a case study in which Emerson Climate Technologies’ System Design Simulator, a steady-state system modeling tool, was used to evaluate design options rather than implementing the changes incrementally in a laboratory test and evaluating the results of each change. Simulation software has proven to drastically reduce development time and cost by limiting the need for expensive and time consuming laboratory testing. Three different system types were used in this study to show the capability of the model and identify design options for improving performance. The three system types were: 3 Ton Air Source Heat Pump: It was selected as it is the most common system using conventional round tube finned heat exchangers in indoor and outdoor units. 5 Ton Heat Pump Pool Heater: This unit was selected to show SDS’s ability to model other system types. It uses coaxial heat exchanger in the outdoor unit and round tube finned heat exchanger in the Indoor Unit. . 2.5 Ton Residential Split System with a Micro Channel Condenser: Unit is equipped with Micro Channel condenser in the outdoor unit whereas the indoor unit has round tube finned heat exchanger. Methodology Several design options that may improve performance were identified for all three systems but only design options for the 13.7 SEER, 3 ton Heat Pump will be presented, including validation runs for the other two systems. Targeted performance testing was used to validate the modeling tool during the re-design exercise. For simplicity, the following parameters are investigated in this exercise: 1. Optimize refrigerant charge by managing compressor Superheat and Condenser Subcooling) and superheat). 2. Optimize refrigerant circuits in indoor and outdoor coils. 3. Change to higher efficiency fan motors in indoor and outdoor units. 4. Optimizing the air flow rate in indoor and outdoor units. 5. Effect of smaller displacement compressor. 6. Evaluate effect of two-capacity compressor. The overall SEER for the final system configuration was 15.8 Btu/Wh resulting in gain of about 16%. Breakdown of gain from each design option will be listed. Using the simulation tool to model the system and analyze numerous design changes eliminated several weeks of laboratory testing and evaluation. While the real cost of engineering time varies by organization, it can safely be shown that there was a significant cost saving associated with using the simulation tool. It also offers opportunity to streamline the product development process and speed of the time it takes to get new products to market

EFFECT OF CYCLIC MEDITATION ON CAREGIVERS STRESS AMONG FAMILIES OF CHILDREN WITH DEVELOPMENTAL DISABILITIES

Background and Objectives: The study explored the effect of Cyclic meditation in reduction of stress levels and enhancement of coping skills of parents of children with developmental disabilities. The research was a single group pre-post study, with convenient sampling, with a sample size of 40, all parents, primary caregivers of the children. This study used both objective and subjective measures to analyse stress and related coping skills. Methods and Materials: 40 Parents, in the age group of 30-45 years, who gave informed written consent participated in the intervention, completed the study. All participants were parents and the primary caregivers of special needs children. The variables GSR - Galvanic Skin Response, Perceived Stress and Coping in relation to Caregiving, and Social Support, were assessed using GSR sensor, CHIP and KCSS questionnaires before and after Cyclic Meditation (CM). All the participants underwent CM practices for 3 days a week for 40 minutes a day, for 8 weeks with a 2 month follow up. The parameters were repeated after 8 weeks.Results: A paired-samples t-test was conducted to compare the pre - post data, in both the objective and subjective measures, used in the study. There was a significant difference in the GSR scores for Pre-CM and Post-CM conditions; and this was significant with p = .001. The CHIP and KCSS scores did not show a statistical significance between the pre - post data. Conclusion: The study did not show a significant difference in the pre-post data of the subjective measures but there is a difference which the study failed to detect, because the study was too small, and it lacked power. However, in the objective measure of GSR to measure the stress levels, the mean GSR is significantly lower than the baseline data (p<0.05), showing that Cyclic Meditation has produced a highly significant reduction in stress levels in the participants

Real Options and Software Upgrades: An Economic Analysis

This work extends earlier work on software upgrades as well as research on real options and IT investment. We consider a two-period model with one software provider who develops and releases a software product to the market. The result shows that the profit from the upgrade policy increases when the market size uncertainty increases. The option value of upgrade is higher when there is more market uncertainty. Also, the value of investing in design effort is more when the development cost is low

Improving Performance of an Existing Heat Pump: A Case Study

Improving Performance of an Existing Heat Pump: A Case Study Vijay Bahel, Scott Lanzer and Suresh Shivashankar Emerson Climate Technologies Sidney, Ohio 45365, USA Phone: 937-498-3643, Fax: 937-498-3203 Email: [email protected] Abstract This paper presents the findings of a case study used to identify the design options for upgrading the performance of an Air Source Heat Pump with minimum design changes to the system chassis. We used Emerson’s Steady-State System Model to identify opportunities for improving the baseline SEER. Our starting point was a nominal Fixed Capacity 5 ton, 14 SEER Heat Pump using Refrigerant R-410a. In this exercise we identified opportunities to improve SEER by selecting a Variable Speed: (i) Compressor, and (i) Indoor and Outdoor Fans. These changes are relatively easy to implement and don’t require changes in the indoor and outdoor heat exchanger surfaces, circuiting etc. Additional improvements opportunities were found by optimizing Refrigerant Charge. SEER changed from 14.0 Btu/Wh to 16.6 Btu/Wh a gain of about 19%. We ended with a HSPF value of 10.6 Btu/Wh. As a first step, several Scroll Variable Speed Compressors models with different rated capacities and efficiencies were evaluated. Once the system model identified the best compressor candidate, we performed a validation run in the laboratory to confirm the findings of the system model before determining the other design options. Our findings show that the model provides excellent correlation between measured and simulated results. Next, we simulated several cases with different combinations of Compressor Speeds and Indoor and Outdoor Air Flow Rates for maximizing Cooling and Heating Performances. An additional benefit of the Indoor Fan Strategy is improved dehumidification with a lower Sensible Heat Ratio for cooling mode and higher delivered temperature for heating mode operation. We next performed simulations to find the best refrigerant charge for various combinations of Subcooling and Compressor Superheat settings. Once the design options were identified we proceeded to validate the simulated results with experimental data per guidelines listed in AHRI Standard 210/240 for both cooling and heating mode operation. Our findings show, the model’s accuarcy is within 5% for a variety of operating conditions. Using the simulation tool to model the system and analyze numerous design changes can eliminate several weeks of expensive laboratory testing and evaluation. While, the real cost of engineering time will vary by organization, it can safely be shown that there is a significant cost benefit associated in using the model to rapidly identify design options. It also offers opportunity to streamline the product development process and speed of the time it takes to get new products to market

Osteolipoma of buccal mucosa: case report and literature review

Osteolipoma affecting oral cavity is indeed rare. We hereby report a case of osteolipoma affecting buccal mucosa. A review of literature of osteolipoma of oral cavity, particularly on radiographic/imaging findings was done. Only 16 cases of Osteolipoma of oral cavity are reported in the literature. The radiographic findings of our case, i.e. multiple dense homogenous radio-opaque structures was reported earlier only in one case [out of 16] of osteolipoma of oral cavit

Markers of cognitive function in individuals with metabolic disease: Morquio Syndrome and Tyrosinemia Type III

We characterized cognitive function in two metabolic diseases. MPS–IVa (mucopolysaccharidosis IVa, Morquio) and tyrosinemia type III individuals were assessed using tasks of attention, language and oculomotor function. MPS–IVa individuals were slower in visual search, but the display size effects were normal, and slowing was not due to long reaction times (ruling out slow item processing or distraction). Maintaining gaze in an oculomotor task was difficult. Results implicated sustained attention and task initiation or response processing. Shifting attention, accumulating evidence and selecting targets were unaffected. Visual search was also slowed in tyrosinemia type III, and patterns in visual search and fixation tasks pointed to sustained attention impairments, although there were differences from MPS–IVa. Language was impaired in tyrosinemia type III but not MPS–IVa. Metabolic diseases produced selective cognitive effects. Our results, incorporating new methods for developmental data and model selection, illustrate how cognitive data can contribute to understanding function in biochemical brain systems

FORMULATION AND EVALUATION OF BILAYER SUSTAINED RELEASE TABLET OF ZOLPIDEM TARTRATE

The purpose of the present study was to develop a bilayer tablet of zolpidem tartrate (ZT) using sodium starch glycolate (SSG) as superdisintegrant in the immediate release (IR) layer and hydrophilic polymers such as hydroxypropyl methylcellulose (HPMC K4M), metalose 90 SH 4000, carbapol 974 PNF in sustained release (SR) layer. Both the IR and SR granules of ZT were evaluated for bulk density, tapped density, angle of repose, Carr’s index, Hausner ratio and loss on drying. All the values were found to be satisfactoy. The prepared bilayer tablets were evaluated for weight variation, hardness, friability, drug content, in vitro drug release, FT-IR studies, similarity factor and stability studies. In vitro dissolution studies were carried out in a USP dissolution apparatus I using 500mL of 0.01N HCl as dissolution medium. The formulations gave an initial burst effect to provide the loading dose of the drug followed by sustained release for 4 h. The data obtained were fitted to Zero order, First order, Higuchi’s model and Korsmeyer-Peppas equations. The release exponent (n) values for all the formulations were less than 0.45 indicating Fickian diffusion was the drug release mechanism. FT-IR studies indicated that there are no drug-excipient interactions. The similarity factor (f2) was calculated by comparing dissolution data of all the formulations with that of marketed bilayer tablet of ZT (Ambien CR). The f2 value was highest (70) for the formulation SF8 and was selected as promising formulation among all the developed formulations. The stability study was performed on the formulation SF8 at 25oC/60% RH, 30oC/75% RH and 40oC/75% RH (accelerated condition) for 3 months. The results indicated that there were no significant changes in aforesaid tablet properties.Key words: bilayer tablets, zolpidem tartrate, sustained release, higuchi’s equation, similarity facto

Nanowires, Nanowire Junctions, and Methods of Making the Same

Disclosed is a nanostructure including a first set of nanowires formed from filling a plurality of voids of a template. The nanostructure also includes a second set of nanowires formed from filling a plurality of spaces created when the template is removed, such that the second set of nanowires encases the first set of nanowires. Several methods are also disclosed. In one embodiment, a method of fabricating a nanostructure including nanowires is disclosed. The method may include forming a first set of nanowires in a template, removing a first portion of the template, thereby creating spaces between the first set of nanowires, forming a second set of nanowires in the spaces between the first set of nanowires, and removing a second portion of the template

Use of neuro-psychiatry medicines in patients with sexual dysfunction: a retrospective study

Background: The objective of the study was to understand the usage of neuro-psychiatry medicines in patients presenting with symptoms of sexual dysfunction.Methods: Medical records of adult patients consulting in the clinic out patients with symptoms of sexual dysfunction were screened for prescriptions of neuropsychiatry medicines. Common neuropsychiatric co-morbidities and prevalence of usage of medicines used for treating neuro-psychiatric disorders was calculated.Results: A total of 628 patients with sexual disorders were included of which 57 (9.1%) had received at least one neuro-psychiatry medicine at the time of presentation. Three most common sexual problems were unconsummated marriage 16 (28.1%), psychogenic ED 14 (24.6%) and organic erectile dysfunction 8 (14.0%). A total of erectile dysfunction 46 (7.3%) patients had psychiatric comorbidity. Five most common neuropsychiatric co-morbidities were anxiety 14 (30.4%), schizhophrenia 10 (21.7%), stress 7 (15.2%), depression 6 (13.0%) and epilepsy 2 (4.3%). The most commonly used neuro-psychiatry medicines were fluoxetine 15 (19.7%), risperidone 11 (14.5%), clonazepam 10 (13.2%), escitalopram 9 (11.8%), alprazolam 5 (6.6%), olanzapine 5 (6.6%) and gabapentin 4 (5.3%). Amisulpride was used in 3 (3.9%) patients whereas valproate, fluoxamine, diazepam and paroxetine were used in 2 (2.6%) patients each. Phenytoin, imipramine, carbamazepine, venlafaxine, haloperidol and sertarline were used in one patient each.Conclusions: Anxiety, schizophrenia and depression are the most common neuropsychiatric disorders in patients with sexual dysfunction. Many patients presenting with sexual dysfunction are already on neuropsychiatry medicines. Further studies are required to evaluate the association between neuropsychiatry medicines and sexual dysfunction in Indian patients. 

Prognostic indicators and patterns of renal recovery in patients requiring hemodialysis for acute kidney injury

Background: The outcome of patients with acute kidney injury (AKI) is highly variable. Patients who receive renal replacement therapy (RRT) for similar diseases may recover differently. The factors that operate in each patient may alter the prognosis and outcome. Aims: Our study aims at identification of prognostic factors influencing recovery in patients who required hemodialysis for AKI. Material and Methods: Patients admitted in different ICUs with AKI who underwent hemodialysis in a tertiary care hospital over a three year period were included in the study. Time from day one of disease to first dialysis, hematological and biochemical parameters were noted. Patients were grouped based on the time taken for recovery of renal function following hemodialysis into group A (<2 weeks) and group B (>2 weeks). Studied parameters have been statistically analyzed to find any significant association with recovery time. Results: Out of 63 patients, 9 progressed to chronic kidney disease. In the remaining 54, Group A comprised 31 and group B 23. Out of all the factors studied, serum creatinine (7.0±1.3 vs 8.4±3.8; P=0.018), S. bicarbonate (21.7±2.8 vs 19.7±3.8; P=0.03), pH at admission (7.25±0.13 vs 7.1±0.19; P=0.048); number of hemodialysis sessions (3.5 ±1.5 vs 5±2.4; P=0.016) and time lag from day one of disease to first hemodialysis (8.6 ± 3.6 vs 11.5±5.9; P=0.007) showed significant association with recovery time. Conclusion: Recovery following AKI is influenced by factors liked delayed presentation, late initiation of hemodialysis, low pH and low bicarbonate which can predict delayed renal recovery following hemodialysis