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Aims/hypothesis Lifestyle interventions are the first-line treatment option for body weight and cardiometabolic health management. However, whether age groups or women and men respond differently to lifestyle interventions is under debate. We aimed to examine age- and sex-specific effects of a low-energy diet (LED) followed by a long-term lifestyle intervention on body weight, body composition and cardiometabolic health markers in adults with prediabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance). Methods This observational study used longitudinal data from 2223 overweight participants with prediabetes in the multicentre diabetes prevention study PREVIEW. The participants underwent a LED-induced rapid weight loss (WL) period followed by a 3 year lifestyle-based weight maintenance (WM) intervention. Changes in outcomes of interest in prespecified age (younger: 25–45 years; middle-aged: 46–54 years; older: 55–70 years) or sex (women and men) groups were compared. Results In total, 783 younger, 319 middle-aged and 1121 older adults and 1503 women and 720 men were included in the analysis. In the available case and complete case analyses, multivariable-adjusted linear mixed models showed that younger and older adults had similar weight loss after the LED, whereas older adults had greater sustained weight loss after the WM intervention (adjusted difference for older vs younger adults −1.25% [95% CI −1.92, −0.58], ppp1c and systolic blood pressure after the WM intervention than middle-aged adults. In the complete case analysis, the above-mentioned differences between middle-aged and older adults disappeared, but the direction of the effect size did not change. After the WL period, compared with men, women had less weight loss (adjusted difference for women vs men 1.78% [95% CI 1.12, 2.43], p1c, LDL-cholesterol and diastolic blood pressure. After the WM intervention, women had greater fat-free mass and bone mass loss and smaller improvements in HbA1c and LDL-cholesterol, while they had greater improvements in fasting glucose, triacylglycerol (adjusted difference for women vs men −0.08 mmol/l [−0.11, −0.04], p Conclusions/interpretation Older adults benefited less from a lifestyle intervention in relation to body composition and cardiometabolic health markers than younger adults, despite greater sustained weight loss. Women benefited less from a LED followed by a lifestyle intervention in relation to body weight and body composition than men. Future interventions targeting older adults or women should take prevention of fat-free mass and bone mass loss into consideration. Clinical trial registration number ClinicalTrials.gov NCT01777893. Graphical abstract

Romania has one of the highest seismic hazard levels in Europe. The seismic hazard is due to a combination of local crustal seismic sources, situated mainly in the western part of the country and the Vrancea intermediate-depth seismic source, which can be found at the bend of the Carpathian Mountains. Recent seismic hazard studies have shown that there are consistent differences between the slopes of the seismic hazard curves for sites situated in the fore-arc and back-arc of the Carpathian Mountains. Consequently, in this study we extend this finding to the evaluation of the probability of collapse of buildings and finally to the development of uniform risk-targeted maps. The main advantage of uniform risk approach is that the target probability of collapse will be uniform throughout the country. Finally, the results obtained are discussed in the light of a recent study with the same focus performed at European level using the hazard data from SHARE project. The analyses performed in this study have pointed out to a dominant influence of the quantile of peak ground acceleration used for anchoring the fragility function. This parameter basically alters the shape of the risk-targeted maps shifting the areas which have higher collapse probabilities from eastern Romania to western Romania, as its exceedance probability increases. Consequently, a uniform procedure for deriving risk-targeted maps appears as more than necessary.

The spatial correlation of ground motions is a subject extensively analysed in the literature, with many studies obtaining spatial correlation models for different datasets, using multiple ground motion prediction equations for various ground motion parameters, being a necessary tool in assessing the seismic risk of building portfolios or spatially distributed systems. A subject tackled mostly for shallow earthquakes datasets, in recent months, two studies considering a database consisting of strong ground motions generated by earthquakes originating from Vrancea intermediate-depth seismic source have been developed. The differences between the two studies consist of the approach in obtaining the correlation model, directly evaluating the correlation coefficients and using the semivariogram approach. A comparison of the two studies is made, resulting in different decay ratios for the same ground motion parameter, the main reasons being the restrains encountered in the first methodology and the subtraction of some ground motion records in the second study. An investigation regarding the influence of the dataset is performed by developing a correlation model for an adjusted dataset using the direct approach. Comparisons with other available models are performed, revealing higher correlation values and more gradual decays for the two studies discussed here, which is mainly caused by the different seismo-tectonic context of the Vrancea intermediate-depth source.

Power ramp limitation (PRL) is likely to become a requirement for large-scale photovoltaic power plants (LPVPPs) in order to allow the increase of PV penetration levels. Especially in islands with reduced inertia capability, this problem is more stringent: high-power ramp can be caused by either fast irradiance changes or other participant generators for example wind power, or loads. In order to compensate for the power mismatch, LPVPPs must use active power reserve (APR), by either curtailment or auxiliary storage. The paper proposes a PRL control structure for dynamic APR sizing and deployment. The selected test case is the power system of Puerto Rico (PREPA), modeled using the modified IEEE 12 bus benchmark system, with different levels of PV penetration. It is shown that LPVPP with PRL can effectively reduce the ramping rate of the participating generators. Considering that the large area of LPVPPs acts as a filter against fast irradiance changes, the study also reveals the required plant size for which an auxiliary storage is no longer needed in order to comply with PRL requirements—an important economical aspect.

The total installed capacity of photovoltaic (PV) power, within each year, constantly pressures transmission system operators to continuously upgrade their network codes (NCs) moving their focus to grid stabilization features. The NCs started to demand large-scale PV power plants (LPVPPs) to synthetically inherit frequency support functions from the conventional generation-frequency sensitive mode (FSM) and encourage the use of inertial response (IR) along with a minimum supply of active power reserves (APRs). This paper investigates the impact of LPVPPs supplying mandatory FSM enhanced with high-sensitivity IR over the frequency quality parameters. Moreover, the paper performs a time-domain evaluation combined with a statistical analysis of the generated synthetic frequency. The main purpose is to demonstrate the short-term and midterm benefits brought by the added ancillary services and to prove their need with increased levels of PV penetration. This paper realizes a complete representation of a power system having modeled the generic IEEE 12 bus system evaluated over a real-time digital simulator platform. The power system model is enhanced with an automatic generation control system and subject to a realistic Danish winter load profile to create the synthetic frequency of the grid. LPVPPs with APRs and frequency support functions share part of the control responsibilities and show their contributions for short-term and midterm frequency stability once the penetration level reaches higher levels.

Large-scale integration of renewable energy sources in power system leads to the replacement of conventional power plants (CPPs) and consequently challenges in power system reliability and security are introduced. This study is focused on improving the grid frequency response after a contingency event in the power system with a high penetration of wind power. An energy storage system (ESS) might be a viable solution for providing inertial response and primary frequency regulation. A methodology has been presented here for the sizing of the ESS in terms of required power and energy. It describes the contribution of the ESS to the grid, in terms of inertial constant and droop. The methodology is applied to a 12-bus grid model with high wind power penetration. The estimated ESS size for inertial response and primary frequency regulation services are validated through real-time simulations. Moreover, it is demonstrated that the ESS can provide the response similar to that provided by the CPPs.

The main objective of this paper is to obtain an empirical relationship for the displacement amplification coefficient, from strong ground motions recorded in Vrancea intermediate-depth earthquakes. To this end, we collected strong ground motions recorded from the Vrancea earthquakes of August 30, 1986 and May 30 & May 31 1990. The computation of the ratio between the inelastic displacements and the elastic displacements was performed for multiple values of the behavior factor (q). The non-degrading Takeda hysteretic model was used in the analysis, with a damping ratio of 5 %. The analysis results were sorted in several bins as a function of several parameters. Mean and standard deviation values of the ratios of inelastic to elastic spectral displacement demands were calculated for each earthquake and each bin, as well as for the entire database. Through a non-linear regression analysis an empirical relation for the displacement amplification coefficient was obtained.

Active Power Reserves (APRs) provided through curtailment (iAPRs) or through auxiliary storage systems (aAPR) with Large scale PV Power Plants (LPVPPs) becomes a reality in the near future with high penetration levels of Photovoltaic (PV) power into the grid. Therefore, this paper analyses the solutions for iAPR fulfilment in central inverter based - LPVPPs in terms of their layout, configuration and control architecture. During iAPR supply, the LPVPP has to operate under its Maximum Power Point (MPP), which means that the MPP algorithm has to undergo several changes. For this purpose, the paper proposes to supply iAPRs by means of a sweep function distributed over the PV inverters used in the central inverter station which has the potential to guarantee a maximum energy extraction along with a secured supply of the APR in any given meteorological condition.

Photovoltaic (PV) power generation started to become a mature technology and large scale PV Power Plants (PVPPs) operating in Maximum Power Point Tracking (MPPT) are not a solution anymore. During changes in the meteorological conditions, PVPPs output is directly influenced creating high power ramps inducing short-term voltage and frequency instabilities into the power system. System operators in countries with increased PV penetration started to become more and more conservative regarding their operation creating strict Grid Codes (GCs). As a proven fact European Network of Transmission System Operators for Electricity (ENTSO-E) pushed the limit one step forward involving PVPPs to contribute with ancillary services even to frequency support. The goal of the paper is to present PVPPs with power ramp limitation and frequency support capabilities without involving any storage equipment. This is achieved by setting the PVPP under its MPP and ensuring a certain amount of reserve. The nature of the reserve has a dynamic character, being released during transients in irradiance and frequency. The entire components of the system are modeled in RSCAD and the performance evaluated on a Real Time Digital Simulator (RTDS).

The increased amount of Photovoltaic (PV) power installed into the power system every year places this renewable way of producing electricity on the third position in the renewable sources hierarchy after hydro and wind solutions. Having significant levels of renewable power penetration into the system led to stability concerns of the entire system affecting its reliability and availability. In consequence system operators such as the European Network of Transmission System Operators for Electricity (ENTSO-E) had an immediate response imposing strict operating regulations in order to keep the system stable and harmonize the operation of the renewable plants with the entire system. For this purpose valid grid benchmarks such as IEEE 12 bus system for High Voltage (HV) and Cigre benchmark cell model for Medium Voltage (MV) have to be developed, tested together and prove that in the future power system with large PV penetration levels on every level, the system continues to be reliable and redundant.

The challenge to bring down the cost of producedphotovoltaic (PV) power had a major impact on the PV marketand in consequence the grid operators experienced higher andhigher PV power penetration. The growing share of thisdecentralized generation plants started to affect the gridstability and Distribution System Operators (DSOs) had to keepthe safety and reliability of the network under strict rules andregulations. The aim of the paper is to realize a survey of recentGrid Codes (GC) and regulations for grid connected PVsystems. The focus is on grid interface requirements, powerquality concerns and Anti-Islanding (AI) issues regarding PVsystems connected to low voltage (LV) and medium voltage(MV) levels of the network.

The growth of world energy demand and the environmental concerns lead to an increase of renewable energy production over the last decade. The increased number of grid-connected photovoltaic (PV) systems gave rise to problems concerning the stability and safety of the utility grid, as well as power quality issues. Lately, PV generators are required, according to the new German Grid Code (GC), to contribute to the grid stability and to provide grid classical functions during normal and abnormal operation. The purpose of this article is to investigate and optimize the standard voltage regulation methods for low voltage (LV) grid-connected PV systems. Reactive power supply strategy proposed by the German GC Q(U) is investigated and simulated performing load flow analysis on a European residential network benchmark. In order to improve the reactive power transfer in the system, an optimized algorithm of voltage regulation is designed with the aim of minimizing the losses in the system for a better integration of PV power generation into the grid.