Solar power generation intermittency and aggregation.

The inherent intermittency of solar power due to diurnal and seasonal cycles has usually resulted in the need for alternative generation sources thereby increasing system operation costs. However, when solar power is spread over a large geographical area with significant time differences, the intermittency can be significantly reduced and also the electricity market balancing cost. The aim of this article is to address the fundamental scientific question on how the intermittency of solar power generation is affected by aggregation, which is of great interest in the wider power and energy community and would have profound impacts on the solar energy integration into the energy supply and Net-Zero Implementation. This article goes beyond the typical regional analysis by investigating solar power intermittency at 5 aggregation levels from a global perspective based on global 7 year hourly meteorological re-analysis data with a fine spatial resolution of [Formula: see text]. In the proposed assessment framework, a coefficient of variation (CV) is used to quantify solar power intermittency and hence characterize the potential benefits of wide area solar power aggregation. A duration curve is used to characterize the intermittency in terms of power availability and a probability density function is further employed to investigate the dispersion and scaling behavior of CV at different aggregation levels. The findings indicate that the CV of solar power generation of 'Inner Mongolia' in China drops from 129.65 to 105.65% in the level of 'Asia' (by 24% decrease), to 56.11% in 'Asia-North_America' (by 73.54% decrease) and to the smallest 43.50% in 'Global' (by 86.15% decrease), nearly 3.5 times of that in 'Asia'; (b) the availability of solar power generation increases from 52.17% in Germany, to 73.30% in 'Europe_EU_plus', to 77.82% in 'Europe', to 98.59% in 'Europe-North_America' (80.60% in 'Europe-Africa', 96.90% in 'Europe-Asia'), to 100% in 'Global'. Finally, conclusions and recommendations are provided to support a Net-Zero strategy.

A Guide to Performance Evaluation for the Intensivist: Ongoing Professional Practice Evaluation and Focused Professional Practice Evaluation in the ICU.

OBJECTIVES: In 2008, The Joint Commission implemented a new standard mandating a detailed evaluation of a provider's performance. The Ongoing Professional Practice Evaluation was designed to provide ongoing performance evaluation as opposed to periodic evaluation. The Focused Professional Practice Evaluation was designed to evaluate the performance of providers new to the medical staff or providers who are requesting new privileges. To date, we are unable to find critical care specific literature on the implementation of Ongoing Professional Practice Evaluation/Focused Professional Practice Evaluation. The purpose of this concise definitive review is to familiarize the reader with The Joint Commission standards and their application to Ongoing Professional Practice Evaluation/Focused Professional Practice Evaluation design and implementation, literature review in the noncritical care setting, and future process optimization and automation. DATA SOURCES: Studies were identified through MEDLINE search using a variety of search phrases related to Ongoing Professional Practice Evaluation, Focused Professional Practice Evaluation, critical care medicine, healthcare quality, and The Joint Commission. Additional articles were identified through a review of the reference lists of identified articles. STUDY SELECTION: Original articles, review articles, and systematic reviews were considered. DATA EXTRACTION: Manuscripts were selected for inclusion based on expert opinion of well-designed or key studies and review articles. DATA SYNTHESIS: There is limited data for the process of Ongoing Professional Practice Evaluation and Focused Professional Practice Evaluation implementation in critical care medicine. Key recommendations exist from The Joint Commission but leave it up to healthcare institutions to realize these. The process and metrics can be tailored to specific institutions and departments. CONCLUSIONS: Currently, there is no standard process to develop Ongoing Professional Practice Evaluation and Focused Professional Practice Evaluation processes in critical care medicine. Departments and institutions can tailor metrics and processes but it might be useful to standardize some metrics to assure the overall quality of care. In the future utilization of newer technologies like applications might make this process less time-intensive.

Using briefing, simulation and debriefing to improve human and system performance.

Safety, effectiveness and efficiency are keys to performance in all high-risk industries; healthcare is no exception, and neonatal-perinatal medicine is one of the highest risk subspecialties within healthcare. Briefing, simulation and debriefing are methods used by professionals in high-risk industries to reduce the overall risk to life and enhance the safety of the human beings involved in receiving and delivering the services provided by those industries. Although relatively new to neonatal-perinatal medicine, briefing, simulation and debriefing are being practiced with increasing frequency and have become embedded in training exercises such as the Neonatal Resuscitation Program (NRP) of the American Academy of Pediatrics (AAP). This chapter will define these terms and offer examples as to how they are used in high-risk activities including neonatal-perinatal medicine.

Using Incentives to Improve Resource Utilization: A Quasi-Experimental Evaluation of an ICU Quality Improvement Program.

OBJECTIVES: Healthcare systems strive to provide quality care at lower cost. Arterial blood gas testing, chest radiographs, and RBC transfusions provide an important example of opportunities to reduce excess resource utilization within the ICU. We describe the effect of a multifaceted quality improvement program designed to decrease the avoidable arterial blood gases, chest radiographs, and RBC utilization on utilization of these resources and patient outcomes. DESIGN: Prospective pre-post cohort study. SETTING: Seven ICUs in an academic healthcare system. PATIENTS: All adult ICU patients admitted to study ICUs during consecutive baseline (n = 7,357), intervention (n = 7,553), and follow-up (n = 7,657) years between September 2010 and August 2013. INTERVENTIONS: A multifaceted quality improvement program including provider education, audit and feedback, and unit-based provider financial incentives targeting arterial blood gas, chest radiograph, and RBC utilization. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the number of orders for arterial blood gases, chest radiographs, and RBCs per patient. Compared with the baseline period, unadjusted arterial blood gas, chest radiograph, and RBC utilization in the intervention period was reduced by 42%, 26%, and 17%, respectively (p < 0.01). After adjusting for potentially relevant patient factors, the intervention was associated with 128 fewer arterial blood gases, 73 fewer chest radiographs, and 16 fewer RBCs per 100 patients (p < 0.01). This effect was durable during the follow-up year. This reduction yielded an approximate net savings of $1.5 M in direct costs over the intervention and follow-up years after accounting for the direct costs of the program. Unadjusted hospital mortality decreased from 7% in the baseline period to 5.2% in the intervention period (p < 0.01). This reduction remained significant after adjusting for patient factors (odds ratio = 0.43; p < 0.01). CONCLUSIONS: Implementation of a multifaceted quality improvement program including financial incentives was associated with significant improvements in resource utilization. Our findings provide evidence supporting the safety, effectiveness, and sustainability of incentive-based quality improvement interventions.

Structure and properties of neutral and cationic gold(III) complexes from substituted 2-(2'-pyridyl)quinoline ligands.

A one-step catalytic synthesis of 6-substituted 4-phenyl-2-(2'-pyridyl)quinolines provides electronically differentiated ligands without solvent, inert atmosphere, metal contamination, or chromatography. Gold(III) complexes formed from these bidentate PyQuin ligands were characterized and studied by single-crystal X-ray diffraction. The cationic gold(III) chloride synthesized from 6-methoxy-4-phenyl-2-(2'-pyridyl)quinoline has a distorted square-planar ligand environment. Diamagnetic neutral gold(III) complexes from methoxy-, methyl-, and phenyl-PyQuin ligands exhibit a long axial Au-N2 interaction.

Application of fractal flocculation and vertical transport model to aquatic sol-sediment systems.

In estuarine and coastal environments, flocculation occurs between particles of different fractal dimensions and of different densities. Questions remain concerning the level of detail required to model particle flocculation and settling in these heterogeneous systems. This paper compares the goodness of fit between two flocculation models, using measured time series particle size distribution data collected from clay, colloidal silica, emulsified crude oil, clay-crude oil, and silica-crude oil systems. The coalesced sphere (CS) flocculation model includes the effects of heterogeneous particle size and density; the modified coalesced fractal sphere (mCFS) model adds effects due to heterogeneous fractal dimension. Goodness of fit was quantified using values of a minimized objective function, the mean of the sum of the square of the relative residuals (MSSRR). For nearly all tested experimental conditions, MSSRR values varied less than 5% between the CS and mCFS flocculation models. Additionally, collision efficiency values for single-particle-type (alpha(HOMOO)) and dual-particle-type (alpha(HETT)) systems were obtained through parameter regression using the CS and mCFS models. Using the mCFS model, estimated fractal dimension (D) values obtained for clay and clay-oil systems were between 2.6 and 3.0, lower than that postulated by the CS model but higher than that estimated experimentally by the particle concentration technique. The Stokes settling velocity of a clay aggregate of a given mass is reduced with decreased fractal dimension. This results in clay-oil flocculation occurring faster than floc sedimentation in the studied hydrodynamic range. Thus, the mCFS model provides insights to the fate of spilled oil in inland and coastal waters.

Modeling crude oil droplet-sediment aggregation in nearshore waters.

This paper describes a modeling approach that simulates changes in particle size distribution and density due to aggregation by extending the Smoluchowski aggregation kinetic model to particles of different density. Batch flocculation studies were conducted for clay, colloidal silica, crude oil, clay-crude oil, and silica-crude oil systems. A parameter estimation algorithm was used to estimate homogeneous collision efficiencies (alphaHOMO) for single-particle-type systems and heterogeneous collision efficiencies (alphaHET) for two-particle-type systems. Homogeneous collision efficiency values (alphaHOMO) were greater for clay (0.7) and for crude oil (0.3) than for silica (0.01). Thus, clay and crude oil were classified as cohesive particles while silica was classified as noncohesive. Heterogeneous collision efficiencies were similar for oil-clay (0.4) and oil-silica (0.3) systems. Thus, crude oil increases the aggregation of noncohesive particles. Data from the calibrated aggregation model were used to estimate apparent first-order flocculation rates (K') for oil, clay, and silica and apparent second-order flocculation rates (K'') for oil and clay in oil-clay systems and for oil and silica in oil-silica systems. For oil or clay systems, aggregation Damköhler numbers ranged from 0.1 to 1.0, suggesting that droplet coalescence and clay aggregation can occur on the same time scales as oil resurfacing and clay settling, respectively. For mixed oil-clay systems, the relative time scales of clay settling and clay-oil aggregation were also within an order of magnitude. Thus, oil-clay aggregation should be considered when modeling crude oil transport in nearshore waters.

Bullying in college by students and teachers.

This study explored bullying in college by students and teachers. The reports of a sample of 1,025 undergraduates indicated that 24.7% had seen students bully other students occasionally and 2.8% very frequently, 5% had been bullied by students occasionally and 1.1% very frequently, 12.8% had seen teachers bully students occasionally and 1.9% very frequently, 4.2% had been bullied by teachers occasionally and .5% very frequently, while 3.2% had bullied other students occasionally and 1.9% very frequently. Male students bullied significantly more than females. Student bullying was predicted by having seen other students bully, and by having been bullied by both students and teachers.

Chemical dispersant effectiveness testing: influence of droplet coalescence.

Thermodynamic and kinetic investigations were performed to determine the influence of coalescence of chemically dispersed crude oil droplets in saline waters. For the range of pH (4-10) and salinity (10 per thousand, 30 per thousand, 50 per thousand ) values studied, zeta-potential values ranged from -3 to -10 mV. As the interaction potential values calculated using Derjaguin-Landau-Verway-Overbeek (DLVO) theory were negative, the electrostatic barrier did not produce significant resistance to droplet coalescence. Coalescence kinetics of premixed crude oil and chemical dispersant were determined within a range of mean shear rates (Gm = 5, 10, 15, 20 s(-1)) and salinity (10 per thousand, 30 per thousand ) values. Coalescence reaction rates were modeled using Smoluchowski reaction kinetics. Measured collision efficiency values (alpha = 0.25) suggest insignificant resistance to coalescence in shear systems. Experimentally determined dispersant efficiencies (alpha = 0.35) were 10-50% lower than that predicted using a non-interacting droplet model (alpha = 0.0). Unlike other protocols in which the crude oil and dispersant are not premixed, salinity effects were not significant in this protocol. This approach allowed the effects of dispersant-oil contact efficiency eta(contact) to be separated from those of water column transport efficiency (eta(transport)) and coalescence efficiency (eta(coalescence)).

Characterizing aquatic sediment-oil aggregates using in situ instruments.

The effects of emulsified crude oil and salinity (15, 30 per thousand ) on the steady state aggregate volume distributions and fractal dimensions were determined for a range of mean velocity gradients, (G(m) =5-50 s(-1)). Aggregation was performed in a 40-L cylindrical tank with a 4-blade paddle mixer. Three-dimensional fractal dimensions (D3) and volume distributions were determined using a procedure integrating data from an electrozone and an in situ light scattering instrument. Two-dimensional fractal dimensions (D2) and derived volume distributions were determined using a recently developed submersible flow cytometer equipped with a digital camera and image analysis software. For latex beads or emulsified crude oil systems, the above listed instruments yielded consistent size distributions and fractal dimensions (D2=1.92 +/- 0.16, D3=2.94 +/- 0.12). Mean volume aggregate diameters determined using the FlowCAM were consistently larger that those determined using the LISST-100 or Coulter Multisizer due to aggregate orientations during measurements. With increasing G(m) values, all colloidal aggregates showed increasing D3 values due to reduced aggregate length. Because of the compactness of all the aggregates (D3 >2), D2 values remained constant at 2. Neither salinity nor sediment type significantly affected D2 values calculated for sediment-crude oil aggregates. However, clay-oil aggregates showed higher D3 values than clay aggregates. This suggests that colloidal oil and mixing shear are the more dominant factors influencing aggregate morphology in nearshore waters. Overall, the data suggests that the analysis methods provide consistent size distribution results. However, because of the shear and salinity of coastal waters, resulting aggregates are too compact to estimate their D3 values using image analysis alone.

Partitioning of crude oil polycyclic aromatic hydrocarbons in aquatic systems.

This paper investigates the hypothesis that observed polycyclic aromatic hydrocarbon (PAH) concentrations in an aqueous system are equal to the sum of the organic phase and soluble phase molar concentrations. While the organic phase concentrations are proportional to the PAH mole fraction in the oil, the soluble phase molar concentrations are estimated using Raoult's law. A batch laboratory mixing vessel with a scalable mixing energy was loaded initially at various oil layer thicknesses (0.4-3.2 mm) which correspond to oil surface loadings (40-310 mg/cm2). The vessel was agitated at constant mean shear rates (Gm = 5, 20 s(-1)). Total petroleum hydrocarbon (TPH) samples were taken periodically to estimate the entrainment rate as a function of initial oil layer thickness. TPH concentrations were measured in-situ using a laser scattering instrument (LISST-100) and ex-situ using gravimetric analysis. At a steady-state TPH concentration (>72 h), additional samples were analyzed for PAH concentration using GC/MS analysis. TPH concentrations increased over time according to a first-order kinetic model. Generally, the first-order rate constant and steady-state concentration both increased with increased oil loading and with increased Gm. In addition, measured PAH concentrations correlated well (r2 > 0.96) with those predicted by a partitioning model. These results are useful for assessing the effects of mixing and oil loading conditions on crude oil entrainment and PAH partitioning.