CVR Factors Research Articles

Evaluating cardiovascular disease risk in type 2 diabetes mellitus patients in a tertiary care hospital in Hyderabad, Sindh, Pakistan

Type 2 Diabetes Mellitus (DM) is the most common type of diabetes. The main adverse effect of diabetes type 2 involves a higher risk of cardiovascular disease. Diabetes patients with this type are more likely to suffer cardiovascular problems. Consequently, this study investigated demographics, CVR factors, age, gender, physical activity, BMI, hemodynamics, HbA1c stage, and lipid profile of 120 patients with type 2 diabetes in Hyderabad, Sindh, Pakistan. The current study covered 120 patients with type 2 diabetes, out of which 40 were male (33.3%) and 80 were female (66.6%), aged 50 to 70. Out of these 120 patients, 17 (14.1%) had coronary artery disease, 15 (12.5) had atherosclerosis, and 8% (6.6) experienced a stroke, according to the findings. Approximately 37.5% of patients had overweight obesity, 54% had poor diabetes control, and 10% had reasonable control based on their HbA1c readings. Furthermore, 55% were hypertensive, and around 12.5% had both macro and microvascular problems. In general, around 33.3% of all Type 2 DM patients have cardiovascular diseases (CVD), indicating that patients with Type 2 DM have a greater risk of increasing CVD. As a result, proper strategies should be implemented to avoid catastrophic outcomes and disease development.

Energy Savings for Various Residential Appliances and Distribution Networks in a Malaysian Scenario

This paper presents a detailed study of the energy savings that can be achieved through residential appliances by implementing conservation voltage reduction (CVR). The computed energy savings are derived from the ZIP coefficients of a load model (static) under varying voltage conditions that represent the power consumed by each appliance tested. Multiple studies have shown energy savings at the substation level but not at the level of a specific residence and appliance; hence, the latter is the focus of this analysis. The appliances are determined based on the type of heating and cooling loads, and the daily duration of use for each appliance, which contributes to the total monthly consumption that is billed for a household are included in this study. Energy savings in Malaysia has been a focus of many current studies, and this study is the first attempt to achieve energy savings through the implementation of CVR. No published work has compared individual appliances that truly benefits from CVR, and this is addressed in this study. The main contribution of this study is that it provides very detailed and measured data that are used to analyze and generate energy savings for very specific residential appliances intended to meet every 1% voltage drop. The load model is developed for the common household appliances in Malaysia, and then a voltage reduction study is applied to the appliances as well as the Malaysian distribution networks. Here, we also provide insight for performing voltage reduction at an electric vehicle (EV) charging station in Malaysia. The results of this study should serve as a foundation for all practicing utilities engineers to address the issue of CVR in Malaysia. The CVR factors for residential, commercial, and industrial networks in Malaysia are also published in this paper.

Assessment of Conservation Voltage Reduction in Distribution Networks with Voltage Regulating Distribution Transformers

The application of voltage reduction in medium and low voltage grids to reduce peak power demand or energy consumption has been implemented since the 1980s using several approaches. Conservation Voltage Reduction (CVR), as one such approach, uses a voltage control device to reduce or increase the voltage setpoint on a busbar, thereby reducing or increasing the amount of active and reactive power supply in the network. Voltage regulation for CVR is always implemented according to established network planning standards in each country. Research in this field has proven that a CVR factor (CVRf) of 0.7–1.5 for peak demand reduction can be achieved. This is an evaluation metric of CVR. The aim of this research is to determine and validate CVRf for peak demand reduction by comparing actual results obtained during regular tap changes with other randomly distributed periods outside tap change operations, using a set of measurement data. It is important to understand CVR deployment capability by evaluating CVR potentials from historical random tap operations before a robust network-wide deployment is introduced. This research provides such guidance. It also provides a novel approach to determining tap changes from voltage measurements using a time-based algorithm. A CVRf ranging from 0.95 to 1.61 was estimated using a measurement dataset from a test field. The result of the entire evaluation shows that the CVRf are smaller during peak PV production and greater during peak demand periods. Further evaluation using statistical hypotheses testing and a control chart was used to validate the evaluation.

Robust Conservation Voltage Reduction Evaluation Using Soft Constrained Gradient Analysis

Evaluation of conservation voltage reduction (CVR) factor is critical to peak load reduction, 556 energy conservation, and many CVR-related power system control/optimization strategies. This paper proposes a novel robust CVR factor evaluation method using soft constrained gradient analysis based on time-varying load modeling and real utility field measurements. Firstly, the time-varying ZIP parameter identification is formulated as an over-determinant problem composed of first-order gradient with respect to each coefficient and soft constraints representing temporal correlation of loads in each time step, in order to improve the robustness and smoothness of CVR factor evaluation. Then, problems in time series are coordinated with a sliding window approach. A necessary condition for selecting the smallest window size is proposed and strictly proved to guarantee the existence and uniqueness of the solution of time-varying load modeling problem. Finally, time-varying CVR factors are accurately and robustly calculated with field measurements and the identified load model. Case studies are performed using sufficient field measurements obtained from two real utilities. Unlike existing methods that require a large number of measurements to obtain precise estimation of CVR factor, the proposed method is sufficiently accurate even when the measurements are limited or of low time resolution. Further, the accuracy and robustness of the proposed approach are validated under different types of uncertainties and compared with other existing data processing and CVR factor evaluation methods.

Integrated Approach to Cardio-Vascular Risk in Insulin-Treated People with Diabetes based on the "Heart Project" and on Metabolic Complications Expected from Incorrect Injection Practice-Related Lipohypertrophy

Type 2 diabetes (T2DM) is known to be associated with increased cardiovascular (CV) morbidity and mortality. Over time, the CV Risk of patients with T2DM has been assessed according to various methods, often borrowed from different populations. Nevertheless, never have been evaluated changes in insulin absorption due to improper injection technique and responsible for further, well recognized CV-R factors as high glycemic variability, frequent hypoglycemia, and unsatisfactory glycemic control. Aim of the study was to intensify diabetes and its own comorbidities treatment, and in addition reduce the impact of injection technique of insulin to evaluate possible improvement in the CV-R score and NHYA score in 4499 insulin-treated T2DM subjects with (LH+) and without lipohypertrophy (LH-) due to improper injection habit. The educational training and the treatment intensification significantly reduced glycemic control, hypoglycemia rate and the mean amplitude of glycemic variability, expecially in LH+ subjects, adding new knowledge to a global intervention addressed to reduce the devastating impact to the increased cardiovascular risk of diabetic people, inclusive of the risk due to LHs

Online Assessment of Conservation Voltage Reduction Effects With Micro-perturbation

Online assessment of conservation voltage reduction (CVR) has great effects on the performance of CVR-based applications, especially for real-time CVR-based controls. The challenges of online CVR assessment mainly come from time-varying load composition and inevitable noise. Besides, the dynamic process resulting from motors further complicates this problem. This article proposes a micro-perturbation based load-to-voltage (LTV) process identification method to online assess the CVR effects. In particular, we construct a well-designed pseudo-random-binary-sequence voltage perturbation to excite the CVR process continually and fully. With the experimental data, the CVR factor and transfer function of LTV are estimated by the cross-correlation method, which can reflect both steady-state and dynamic CVR effects without being affected by noise. The proposed method is verified on a specific hardware-in-the-loop testbed under various cases. In addition, through the energy-saving and power smoothing applications, the impact of CVR assessment on performance of CVR-based applications is also analyzed, which further verify the validity and economic benefits of the proposed assessment method.

Cardiovascular risk screening of patients with serious mental illness or use of antipsychotics in family practice

BackgroundPatients with serious mental illness (SMI) and patients on antipsychotics (AP) have an elevated risk for cardiovascular diseases. In the Netherlands, the mental healthcare for these patients is increasingly taken care of by family practitioners (FP) as a result of a shift from secondary to primary care. Therefore, it is essential to increase our knowledge regarding the characteristics of this patient group and the (somatic) care provided by their FPs. The aim was to examine the rate of cardiovascular risk screening in patients with SMI or the use of AP in family practice.MethodsWe performed a retrospective cohort study of 151.238 patients listed in 24 family practices in the Netherlands.From electronic medical records we extracted data concerning diagnoses, measurement values of CVR factors, medication and frequency of visits over a 2 year period. Primary outcome was the rate of patients who were screened for CVR factors. We compared three groups: patients with SMI/AP without diabetes or CVD (SMI/AP-only), patients with SMI/AP and diabetes mellitus (SMI/AP + DM), patients with SMI/AP and a history of cardiovascular disease (SMI/AP + CVD). We explored factors associated with adequate screening using multilevel logistic regression.ResultsWe identified 1705 patients with SMI/AP, 834 with a SMI diagnosis, 1150 using AP. The screening rate for CVR in the SMI/AP-only group (n = 1383) was adequate in 8.5%. Screening was higher in the SMI/AP − +DM (n = 206, 68.4% adequate, OR 24.6 (95%CI, 17.3–35.1) and SMI/AP + CVD (n = 116, 26.7% adequate, OR 4.2 (95%CI, 2.7–6.6). A high frequency of visits, age, the use of AP and a diagnosis of COPD were associated with a higher screening rate. In addition we also examined differences between patients with SMI and patients using AP without SMI.ConclusionCVR screening in patients with SMI/AP is performed poorly in Dutch family practices. Acceptable screening rates were found only among SMI/AP patients with diabetes mellitus as comorbidity. The finding of a large group of AP users without a SMI diagnosis may indicate that FPs often prescribe AP off-label, lack information about the diagnosis, or use the wrong code.

국내 배전계통에서의 CVR 계수 추정 및 경제적 효과 분석 적용 방안

In this paper, the CVR estimation method is proposed using the direct method. This method calculates the voltage change and the load change for the same time period when the tap of a main transformer in a substation changes. Through these CVR estimation results, economic analysis is conducted by analying the CVR effect of the domestic distribution systems. Based on the estimated CVR factor, a representative model of the domestic distribution system is assumed, and economic analysis is evaluated through CVR effect analysis when CVR control is operated. Demand reduction of a substation and line loss reduction costs are calculated using the CVR factor and voltage reduction. Through this analysis, CVR in distribution systems can be expected to reduce the power loss cost and power plant construction cost.

Conservation Voltage Reduction and Volt-VAR Optimization: Measurement and Verification Benchmarking

The ongoing efforts in grid modernization, which is accompanied by upgrading distribution grids through employment of advanced distribution grid technologies, further provide the necessary tools to employ Conservation Voltage Reduction (CVR) and Volt-VAR Optimization (VVO) programs and ensure that the system is operating continuously at an optimized voltage. This paper provides an overview of CVR/VVO deployments by several electric utilities within the U.S. The paper looks at three major areas: (i) type of the initiative, including pilot, plan, program, study, and test case; (ii) year(s) of the application; and (iii) methodology used for CVR factor assessment. When available, a more detailed discussion on the initiative is provided. Based on the studied cases, it is concluded that majority of utilities use either a regression-based or a comparison-based method. The day-on/day-off approach is common within both methods in which CVR is applied every other day to generate CVR-on and CVR-off data that can be used for comparison and model fitting.

On the Inadequacy of the CVR Factor for Active Schemes

Conservation Voltage Reduction (CVR) is a well-known technique to reduce energy consumption by reducing the supplied voltage within statutory limits. Historically, the efficacy of CVR schemes has been quantified using the CVR factor (CVRf) which relates, in a given period, voltage reduction to energy savings. This metric has proved useful in the past, where fixed voltage reductions were applied. However, this letter shows from a theoretical perspective and with a realistic case study that when used for active CVR schemes (voltages actively controlled throughout the day), the CVRf can be smaller than that for fixed voltage reductions despite the larger energy savings. This could be misleading for decision makers considering active CVR schemes as an energy efficiency measure. Consequently, it is recommended that comparisons among CVR schemes are carried out in terms of actual energy reductions.

Comparison of Time-Varying Load Models for Estimating CVR Factor and VSF Using Dual-Stage Adaptive Filter

Assessment of conservation voltage reduction (CVR) deployment largely depends on load-to-voltage sensitivity (LTV). Therefore, two quantifiers—voltage and the load consumption—are truly responsible for measuring the CVR factor (CVRF), which is the primary index for calculating the load or energy consumption reduction. Simultaneously, CVR deployment improves the voltage profile by providing line relief due to the reduction in consumption. Hence, it is also important for the utilities to know the voltage sensitivity factor (VSF) during the CVR deployment period. This paper provides a comprehensive comparison of two different voltage sensitive load models—ZIP and exponential model—to estimate the CVRF and the VSF. The comparison is done in a time varying manner since the parameters of load models vary with time as the voltage changes. Two different sets of dual-stage filtering methods are used to estimate the load parameters and observe which load model accurately identifies the CVRF and the VSF. Stochasticity in load variation is also considered in the estimation process. This process helps the utilities to assess the CVRF and VSF for a target feeder using the most accurate load model. The entire estimation is done using actual data from a 22.86 kV distribution feeder, provided by duke energy progress. Moreover, the validation of the estimated parameters is done using the original circuit associated with the measurements in OpenDSS Software.

Multidisciplinary approach to obesity: Aerobic or resistance physical exercise?

BackgroundAn integrated treatment based on dieting, physical training and cognitive-behavioural psychotherapy is an effective tool to reduce obesity and its consequences. However, the feasibility of this approach is problematic. This study aims to compare two multidisciplinary programs used to improve weight loss. MethodsFifty-two obese individuals were subjected to an Enhanced Lifestyle Counselling associated with, according to their own choice, dieting (N = 11), or dieting + aerobic training (n = 18), or dieting + resistance training program (n = 23). The study experiment spanned 16 weeks divided into two phases. The first phase lasted 04 weeks and was oriented to enhance motivation and establishing changes in behaviours related to dietary and sedentary lifestyle. The second phase lasted 12 weeks and was oriented to add aerobic or resistance training. Body compositions, cardiovascular disease risk factors, and cardio-respiratory fitness were assessed. ResultsData demonstrated that all obesity treatment programs were able to improve all studied variables. Weight loss levels were −6.03 ± 2.08, −10.5 ± 2.33, and −9.37 ± 1.99 kg in Dieting, DAT and DRT groups, respectively. Our results noted also that exercise training could play an important role in reducing obesity and its consequences. Nevertheless, modifications were more important in DRT at the explosivity and muscle strength and in DAT at fat percentage, aerobic capacity, SA, and CVR factors. ConclusionThe current evidence noted that both multidisciplinary weight loss programs were efficient in the treatment of obesity and its comorbidity. Moreover, the use of aerobic exercises was more effective in reducing body fat and improving cardiorespiratory fitness. However, using resistance exercises appeared to be more appropriate to enhance the muscle potential.

Robust Time-Varying Load Modeling for Conservation Voltage Reduction Assessment

Due to the increasing penetration of intermittent renewable energy and highly stochastic load behavior, it is challenging to effectively assess conservation voltage reduction (CVR) in power distribution systems. This paper proposes a robust time-varying load modeling technique to accurately identify load-to-voltage (LTV) dependence, yielding an improved CVR assessment scheme. In particular, we propose a robust recursive least squares (RLS) approach to estimate time-varying parameters of a ZIP load model at the substation level. Based on the identified load model, we are able to effectively evaluate LTV and analyze CVR factors. We propose a RLS with variable forgetting factors to capture the variations of model parameters under different situations, including continuous and sudden changes of parameters. To further enable RLS to suppress bad or missing measurements, we advocate to use the Huber M-estimator with a convex cost function. Finally, the robust RLS is solved by an iteratively reweighted technique. We demonstrate the effectiveness and the robustness of the proposed method using both simulations and field tests.

Intergenerational differences in prevalence and association with survival rates of major cardiovascular risk factors

The objective: determination of the prevalence of major cardiovascular risk factors (CVRF) and their association with the survival rate of cardiovascular disease (CVD) among generations 1905–1924 and 1925–1944 years of birth.Materials and methods. 384 patient case histories were analyzed from 1905 to 1944 with ischemic heart disease (IHD). According to the year of birth, the patients were divided into 2 groups: 1 group – born in the period 1905–1924 («pre-war» generation), 2 group – from 1925–1944 (a generation of «front-line soldiers»). The diagnosis was established on the basis of examinations, in accordance with the current recommendations for the diagnosis of IHD.Results. There are significant intergroup differences in the frequency and structure of arterial hypertension in the pre-war generation group, the incidence of arterial hypertension (AH) was 64,1%, of which 54,6% is isolated systolic hypertension (ISAH). In the frontline group, the AH frequency reached 74,1%, and ISAG accounted for only 27%. When analyzing the average of low density lipoprotein (LDL) values in the first and second generations, there were no significant differences. However, gender analysis revealed that in both groups of women, the average level of LDL was higher than that of men. The prevalence of elevated LDL in the first generation is higher (98,68%) than in 2 generations (94,12%) (р>0,05). The prevalence of the increased level of glucose in the 1st generation is 4,4%, while in the 2nd generation it increases to 20,6% (p=0,0001). Although the diagnosis of diabetes mellitus is 1,94% in the 1st group and 3,68% in the second group, which indicates a significant increase in the cases of violation of carbohydrate metabolism in the 2nd generation.Conclusion. Also, with a detailed gender analysis within the group, attention is drawn to the distribution of overweight and obese individuals: if in the 1st generation of overweight men there was more (68,85%) than with obesity (31,15%), and women with increased body weight was 40,38%, with obesity 59,62%, then in 2 generations 61,8% of men were overweight and only 37% obese. In women, a mirror trend was observed – 36,1% were overweight and 63,9% were obese. These CWR factors were associated with various indicators of life. in the first generation there was no dependence of survival on the presence of individual CVR factors; in the second, survival was significantly lower in patients with obesity and hypertension.

Estimation of Conservation Voltage Reduction Factors Using Measurement Data of KEPCO System

This paper describes a method to estimate conservation voltage reduction (CVR) factors using data measured in power distribution systems. A direct method is proposed to estimate CVR factors using only data measured at the moment of the transformer tap change. The mean absolute deviation (MAD) direct method is proposed to consider direct methods and load variations. The proposed methods do not necessitate intentional tap changes for testing purposes. Instead, the voltage and load changes that occur when the tap changes, for voltage regulation purposes, are measured and utilized in the CVR factor calculation. The proposed methods were tested using data obtained from the Korea Electric Power Corporation (KEPCO) system, and the results revealed that CVR factors for both active power and reactive power could be estimated using data measured in power distribution systems. Results of the CVR factor estimation for the active power revealed that the highest CVR factors occurred in winter, during which a large quantity of heating loads exist. In addition, the estimated CVR factors for the reactive power were higher than the estimated CVR factors for the active power because reactive power is more sensitive to voltage changes.

Evaluation of Conservation Voltage Reduction with Analytic Hierarchy Process: A Decision Support Framework in Grid Operations Planning

This paper presents a systematic framework to evaluate the performance of conservation voltage reduction (CVR) by determining suitable substations for CVR in operations planning. Existing CVR planning practice generally only focuses on the energy saving aspect without taking other underlying attributes into account, i.e., network topology and reduced voltage effects on other substations. To secure the desired operating reserve and avoid any adverse impacts, these attributes should be considered for implementing CVR more effectively. This research develops a practical decision-making framework based on the analytic hierarchy process (AHP) to quantify several of the aforementioned attributes. Candidate substations for CVR deployment are prioritized such that performances are compared in terms of power transfer distribution factor (PTDF), voltage sensitivity factor (VSF), and CVR factor. In addition, to meet a specified reserve requirement, an integer programming approach is adopted to select potential substations for CVR implementations. Case studies for a Korean electric power system under diverse operating conditions are performed to demonstrate the effectiveness of the proposed method.

The value of conservation voltage reduction to electricity security of supply

In the specific event that there is not enough electricity being produced in the power market of Great Britain to meet demand, the system operator can use a set of mitigation tools to manage these supply shortfalls that are outside of normal operation of the market and that are used ahead of any controlled customer disconnections. Demand control is an emergency mitigation tool used by the system operator that instructs distribution network operators to implement voltage reduction across the electricity distribution system with the intent of achieving a reduction in customer's demand. The introduction of new low carbon generation and demand technologies in the electricity distribution networks, with fundamentally different technical and operating characteristics from the incumbent technologies, is likely to drive a dissimilar impact on the level of demand reduction that can be achieved through voltage reduction compared to those previously expected. Thus, there is a need to comprehensively understand the effectiveness of the voltage reduction in electricity distribution networks that can be realised through demand control events. The delivery of demand control can be achieved through conservation voltage reduction (CVR) techniques based on the principle of lowering the supply voltage to end-use consumers of electricity in order to reduce the energy consumption of some types of loads while maintaining customer service voltage within statutory limits. This paper presents a methodology to quantify and assess the value of CVR to security of supply of electricity systems. Specifically, it estimates the response of electricity demand to demand control events in the electricity distribution system to reduce customer's demand during periods of significantly low supply-demand margins. The methodology is applied to a network structure representative of the electricity distribution network of Great Britain and the value of CVR is estimated for individual distribution network feeders and for the distribution system over an annual load cycle. The analysis demonstrates that the response of demand to voltage reduction is relatively different from substation to substation, feeder to feeder and especially load to load. The CVR factor for the Great Britain electricity distribution network is assessed to vary on average from 0.81 in the summer season to 1.13 in the winter season. The CVR factors for the electricity distribution network of Great Britain are expressed in the form of a look up table to provide a simple framework for network operators to estimate the response of demand to voltage reduction/demand control events.

Effects of high-impact aerobics vs. low-impact aerobics and strength training in overweight and obese women

Regular exercise is one of the factors determining weight reduction and fat loss, and at the same time it is associated with important health benefits. The purpose of this study was to compare the effects of two different modalities of exercise on changes in body composition, physical fitness, and CVR factors in healthy overweight and obese women. Thirty-two women were randomly assigned in 2 groups: a high-impact aerobics group (HIA, N.=16) and a low-impact aerobics combined with a strength training program group (LIAS, N.=16). Body weight (BW), body composition, aerobic fitness (AF), speed and agility, vertical-jump distance (VJ), abdominal muscle endurance (AME), the flexibility of the lower back and hamstrings, heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP), total cholesterol (TC), triglyceride (TG), HDL-c, LDL-c, apolipoprotein A-I (Apo A-I) and B (Apo B) were measured at baseline and at the end of the training period. A significant decrease was noted in all anthropometric variables excepting fat-free mass (FFM) which increased in LIAS group (P<0.05). Comparisons between groups noted significant differences in favor of HIA group in BW, fat percentage and FM, and in favor of LIAS group in FFM (P<0.05 for all). DBP, HR, TC, LDL-c, TG, and Apo B significantly decreased, and HDL-c and Apo A-I significantly increased in both groups. No significant modifications were noted in SBP and glucose concentrations. Significant improvements in all physical fitness components were also noted in HIA group (P<0.05), however, only the AF, VJ, AME, and the flexibility were improved in LIAS group (P<0.01). Comparison between groups reported that values related to VJ and AME were higher in LIAS compared to HIA group (P<0.01). Our findings noted that a 24-week of HIA or LIAS training improved body composition, physical fitness and CVR factors in overweight and obese women. Nevertheless, the use of each training method remains tributary to wished effects. In fact, HIA training method is more effective in body weight reduction and fat loss, however, LIAS training method is more appropriate when the improvement of FFM, aerobic fitness and muscle strength is claimed.

Time-Varying Stochastic Assessment of Conservation Voltage Reduction Based on Load Modeling

This paper presents a time-varying stochastic technique to assess conservation voltage reduction (CVR) effects based on load modeling. A time-varying exponential load model is developed to represent voltage dependences of loads. The recursive least square (RLS) method is applied to identify model parameters in a recursive way. CVR factors can be calculated using the identified model parameters. The time-varying stochastic model for CVR effects can then be constructed by the Kolmogorov-Smirnov (K-S) test. The proposed CVR assessment method is applied to one-year measurement data from a utility company. The calculated CVR factors are verified by a Euclidian distance-based comparison method. Stochastic models of CVR effects in each time window are constructed. Compared with previous efforts on assessing CVR effects, the proposed method does not require control groups or assumptions of linear relationships between the load and its impact factors. The probabilistic nature of CVR effects is also fully considered.

FRI0076 Need for Statins in Rheumatoid Arthritis Patients with High Cardiovascular Risk: Differences According to European and American Recommendations. the Comedra Study

BackgroundCardiovascular risk (CVR) is increased in RA and should be evaluated annually. EULAR recommends using the SCORE equation to calculate risk, after applying a multiplier of 1.5 in patients with...