Dantec Dynamics (Denmark)

Abstract The distinct characteristics of geothermal wells necessitate a unique and specialized approach to well design. This is critical for prolonging well lifespan and tackling the unique operational challenges present in mature geothermal fields, such as the case on a field in the Philippines. To enhance steam production, geothermal wells often intersect faults and complex geological formations, which result to partial to total fluid losses. These losses introduce significant uncertainty in cementing and compromise its quality. Such issues can lead to channeling, the formation of micro-annuli, and cement degradation — all of which undermine well integrity and reduce production efficiency. Furthermore, these cementing challenges, especially in the case of geothermal wells, may result to having trapped fluid in casing-to-casing annulus that can potentially compromise well integrity due to huge temperature swings that the wells encounter over their operating lives. Addressing these integrity concerns in a cost-effective manner is critical to maintaining safe, efficient, and economically viable well operations over time. To overcome these challenges, Welltec partnered with a geothermal operator in the Philippines to rehabilitate eight geothermal production wells affected by casing collapse and parted casing. A traditional workover involving bridge plugs was deemed impractical, as drilling out the plug risked further damage to liners exposed to corrosive, low-pH fluids. There was also a concern that trapped fluids could trigger additional casing failures. Therefore, a more controlled and precise cementing strategy was required to restore casing integrity. This paper introduces a tailored solution that integrates high-temperature Metal Expandable Packer technology and stage cementing collars. Case studies from a geothermal field in the Philippines illustrate how this approach restores well integrity without the need for a dedicated drill-out run. Building on experience from prior deployments, the improved MEP enables long-string tieback and casing relining to depths of approximately 1,300 meters — previously considered unattainable due to casing collapse, which had limited operations to around 700 meters. New well designs using CRA are also being optimized to benefit from such solution and withstand highly acidic environments. These wells require immediate relining, applying insights from earlier CRA wells in the same field. The MEP system eliminates the need to drill out plugs, thereby preventing damage to CRA casing. Integrating MEP technology into both drilling and workover operations offers a robust strategy to resolve integrity issues that typically lead to early well failure. This geothermal-specific technology enhances repeatability, safety, and operational control, ultimately enabling more reliable and extended utilization of geothermal resources.

Black soldier fly larvae (BSFL) efficiently convert biowaste into valuable animal feed. Sustainable and reliable bioconversion is desirable to achieve optimal economic and environmental outcomes. Thus, science and industry require an accessible research platform to study complex bioconversion processes under conditions mirroring industrial-scale settings. In this study, industry-relevant respiration chambers were designed, tested, and replicated for BSFL feeding trials. Each open-circuit chamber housed three industrial rearing crates. The substrate/frass and air temperature, mass change, NH3 and CO2 emissions, and relative humidity were measured. The design was validated for CO2 recovery, airtightness, airflow homogeneity, and BSFL performance using firstly, a uniform control substrate and secondly, uniform food waste across four parallel chambers. In a third trial, the composition of food waste was varied across parallel chambers to detect differences in metabolic processes. For trials using uniform substrates, low variability across chambers in performance parameters confirmed the reproducibility and comparability of the design (e.g. bioconversion rate: <1%, final larval mass: ≤2 mg, standard deviations, dry matter based). In contrast, the trial with varying food waste compositions showed a strong effect on average substrate/frass temperature (e.g. 31.5°C vs 41.8°C) and final dry larval mass (e.g. 67mg vs 40mg). This is the first study to systematically assess heat generation directly from heterogeneous food waste, a crucial parameter for efficient BSFL bioconversion. These chambers provide an opportunity for science and industry to thoroughly assess and understand the metabolic bioconversion characteristics. The findings are key for the optimisation of sustainable bioconversion processes.

We propose a refinement and validity region expansion process of a 3rd order polynomial calibration based on bundle adjustment. The present methodology can be expanded to any model as long as the mapping is a smooth function. Both methods are tested with a tomographic Particle Tracking Velocimetry measurement whose results are compared in terms of the smoothness and length of the retrieved tracks. The refinement method shows a significant improvement in both the associated PDFs. Similarly, the expansion shows a corresponding behaviour to the original calibration even though a higher degree of smoothness of the tracks is achieved.

Dietary nitrate supplementation has been shown to reduce pulmonary O2 uptake during submaximal exercise and enhance exercise performance. However, the effects of nitrate supplementation on local metabolic and haemodynamic regulation in contracting human skeletal muscle remain unclear. To address this, eight healthy young male sedentary subjects were assigned in a randomized, double-blind, crossover design to receive nitrate-rich beetroot juice (NO3, 9mmol) and placebo (PLA) 2.5h prior to the completion of a double-step knee-extensor exercise protocol that included a transition from unloaded to moderate-intensity exercise (MOD) followed immediately by a transition to intense exercise (HIGH). Compared with PLA, NO3 increased plasma levels of nitrate and nitrite. During MOD, leg and leg blood flow (LBF) were reduced to a similar extent (∼9%-15%) in NO3. During HIGH, leg was reduced by ∼6%-10% and LBF by ∼5%-9% (did not reach significance) in NO3. Leg kinetics was markedly faster in the transition from passive to MOD compared with the transition from MOD to HIGH both in NO3 and PLA with no difference between PLA and NO3. In NO3, a reduction in nitrate and nitrite concentration was detected between arterial and venous samples. No difference in the time to exhaustion was observed between conditions. In conclusion, elevation of plasma nitrate and nitrate reduces leg skeletal muscle and blood flow during exercise. However, nitrate supplementation does not enhance muscle kinetics during exercise, nor does it improve time to exhaustion when exercising with a small muscle mass. KEY POINTS: Dietary nitrate supplementation has been shown to reduce systemic O2 uptake during exercise and improve exercise performance. The effects of nitrate supplementation on local metabolism and blood flow regulation in contracting human skeletal muscle remain unclear. By using leg exercise engaging a small muscle mass, we show that O2 uptake and blood flow are similarly reduced in contracting skeletal muscle of humans during exercise. Despite slower kinetics in the transition from moderate to intense exercise, no effects of nitrate supplementation were observed for kinetics and time to exhaustion. Nitrate and nitrite concentrations are reduced across the exercising leg, suggesting that these ions are extracted from the arterial blood by contracting skeletal muscle.

The corona virus pandemic has imperilled tourist destinations around the world, completely disrupting all types of traffic and border traffic. The global corona virus pandemic has brought with it major changes in trade, industry, agriculture and transportation. The negative effect of the pandemic on agriculture is reflected in the loss of the market. Tourism and catering are affected first, as arrangements are canceled and people go out to restaurants less. The next important branch that got affected is industry due to supply chain disruption. Economic activity has pretty much stalled in many sectors, and yet agriculture and food production are mentioned as saviors of national economies. The maxim is known as "there is no stable state without a consistent agrarian policy and a developed agricultural sector". Tourism is an important activity that is seriously counted on in the municipality of Kučevo. The festival of original folk art "Homoljski motivi" is organized in the municipality, moreover, at the territory of the municipality we can find the gold-bearing river Pek and the attractive caves Ceremošnja and Ravništarka. They are tourist content by which the municipality of Kučevo has long been recognizable. The absence of tourist activity on the territory of the municipality of Kučevo affected the reduction of the tourist offer, such as the preparation of traditional food using local products, which all has a negative impact on agricultural production, primarily livestock products.

Nitrate (NO3-) supplementation resulting in higher plasma nitrite (NO2-) is reported to lower resting mean arterial blood pressure (MAP) and oxygen uptake (VO2 ) during submaximal exercise in non-athletic populations, whereas effects in general are absent in endurance-trained individuals. To test whether physiologic effects of NO3- supplementation depend on local muscular training status or cardiovascular fitness, male endurance-trained cyclists (CYC, n=9, VO2 -max: 64±3mL/min/kg; mean±SD) and recreational active subjects serving as a control group (CON, n=8, 46±3mL/min/kg), acutely consumed nitrate-rich beetroot juice ([NO3-] ~9mmol) (NIT) or placebo (PLA) with assessment of resting MAP and energy expenditure during moderate intensity (~50% VO2 -max) and incremental leg cycling (LEG-ex) and arm-cranking exercise (ARM-ex). NIT increased (P<.001) resting plasma NO3- by ~1200% relative to PLA. Plasma NO2- increased ~25% (P<.01) with a significant change only in CYC. LEG-ex VO2 (~2.60L/min), ARM-ex VO2 (~1.14L/min), and resting MAP (~87mm Hg) remained unchanged for CYC, and similarly for CON, no changes were observed for LEG-ex VO2 (~2.03L/min), ARM-ex VO2 (~1.06L/min), or resting MAP (~85mm Hg). VO2 -max was not affected by supplementation, but incremental test peak power was higher (P<.05) in LEG-ex for CYC in NIT relative to PLA (418±47 vs 407±46W). In both CYC and CON, high initial baseline values and small increases in plasma NO2- after NIT may have lowered the effect of the intervention implying that muscular and cardiovascular training status is likely not the only factors that influence the physiologic effects of NO3- supplementation.

Highly monodispersed emulsions can be produced in microfluidic flow-focusing junctions (Anna et al 2003 Appl. Phys. Lett. 82 364–6, Baroud et al 2010 Lab Chip 10 2032–45). This is the reason why many industrial processes in the medical industry among others are based on droplet manipulation and involve at some point a step of dripping within a junction. However, only a few studies have focused on the flow field inside and outside the droplet, even though it is a necessary step for understanding the physical mechanism involved and for modeling the droplet formation process. Water-in-oil emulsions are produced in flow-focusing junctions of square cross sections. The fluids constituting the emulsion are (i) a 5.0 mPa·s silicon oil for the oil phase and (ii) distilled water containing 2.0 wt% of sodium dodecyl sulfate surfactant for the aqueous phase. Time-resolved shadow particle images are acquired using a microscale particle image velocimetry (µPIV) system and flow fields are calculated using an adaptive PIV algorithm in combination with dynamic masking. Inside the microchannel and in the permanent regime, the droplet has an internal circulation that has been well established by Sarrazin et al (AICHE J. 52 4061–70). But during the formation of a droplet in a flow-focusing junction, the flow field is not so well known, and the circulation in the finger flows forward along the sides and returns along the center. The mechanism can be described in terms of four distinct steps: droplet growth, necking, rupture, and recoil. The liquid expelled from the neck just before rupture is also well observed. The flow field and mixing are measured in detail during a complete cycle of formation of a main droplet and satellite droplets using high-speed imaging. This allows us to develop a better understanding of the different forces that are present and of the physical mechanism of droplet formation.

νZ is a part of the SMT solver Z3. It allows users to pose and solve optimization problems modulo theories. Many SMT applications use models to provide satisfying assignments, and a growing number of these build on top of Z3 to get optimal assignments with respect to objective functions. νZ provides a portfolio of approaches for solving linear optimization problems over SMT formulas, MaxSMT, and their combinations. Objective functions are combined as either Pareto fronts, lexicographically, or each objective is optimized independently. We describe usage scenarios of νZ, outline the tool architecture that allows dispatching problems to special purpose solvers, and examine use cases.