Establishment of a coastal fish in the Azores : recent colonisation or suddenexpansion of an ancient relict population?

The processes and time scales associated with ocean-wide changes in the distribution of marinespecies have intrigued biologists since Darwin’s earliest insights into biogeography. The Azores, amid-Atlantic volcanic archipelago located more than 1000 km off the European continental shelf,offers ideal opportunities to investigate phylogeographic colonization scenarios. The benthopelagicsparid fish known as the common two-banded seabream (Diplodus vulgaris) is now relativelycommon along the coastline of the Azores archipelago, but was virtually absent prior to the 1990s.We employed a multiple genetic marker approach to test whether the successful establishment of theAzorean population derives from a recent colonization from western continental/island populationsor from the demographic explosion of an ancient relict population.Results from nuclear and mtDNA sequences show that all Atlantic and Mediterranean populationsbelong to the same phylogroup, though microsatellite data indicate significant genetic divergencebetween the Azorean sample and all other locations, as well as among Macaronesian, westernIberian and Mediterranean regions. The results from Approximate Bayesian Computation indicatethat D. vulgaris has likely inhabited the Azores for approximately 40 (95% C.I.: 5.5─83.6) to 52(95% C.I.; 6.32─89.0) generations, corresponding to roughly 80-150 years, which suggests nearcontemporary colonisation, followed by a more recent demographic expansion which could havebeen facilitated by changing climate conditions. Moreover, the lack of previous records of thisspecies over the past century, together with the absence of lineage separation and the presence ofrelatively few private alleles, do not exclude the possibility of an even more recent colonisationevent

Transient analysis for leak detection in pipe with fluid-structure interaction

The use of fluid transients has the potential to provide insight into effect of leaks in pipeline systems and hence provide leak detection method. This paper presents a technique for detection and location of leaks in a single pipe by means of transient analysis. The method uses transient pressure waves initiated by the sudden closure of an upstream valve. The presence of a leak in a pipe partially reflects these pressure waves and allows for the location and magnitude of leaks. The two constitutive equations of continuity and momentum yield a set of two partial differential equations of hyperbolic type. The computed results obtained by the method of characteristics describe the influence of the leak on head and discharge time-histories. To put in evidence the fluid-structure, interaction the influence of friction and Young modulus of the pipe wall on the leak detection and sizing is also discussed

Enhancing hydrogen gas production in electrolysis cells with ammonium chloride and solar PV integration

In this study, the electrolysis of water by using ammonium chloride (NH4Cl) as an electrolyte was investigated for the production of hydrogen gas. The assembled electrochemical cell consists mainly of twenty-one stainless-steel electrodes and a direct current from a battery, ammonium chloride solution. In the electrolysis process, hydrogen and oxygen are developed at the same time and collected as a mixture to be used as a fuel. This study explores a technic regarding the matching of oxyhydrogen (HHO) electrolyzers with photovoltaic (PV) systems to make HHO gas. The primary objective of the present research is to enable the electrolyzer to operate independently of other energy origins, functioning as a complete unit powered solely by PV. Moreover, the impact of using PWM on cell operation was investigated. The experimental data was collected at various time intervals, NH4Cl concentrations. Additionally, the hydrogen unit consists of two cells with a shared positive pole fixed between them. Some undesirable anodic reaction affects the efficiency of hydrogen gas production because of the corrosion of anode to ferrous hydroxide (Fe(OH)2). Polyphosphate Inhibitor was used to minimize the corrosion reaction of anode and keep the efficiency of hydrogen gas flow. The optimal concentration of 3 M for ammonium chloride was identified, balancing a gas flow rate of 772 ml/min with minimal anode corrosion. With PWM, conversion efficiency ranges between 93 % and 96 %. Therefore, PWM increased conversion efficiency by approximately 5 %, leading to a corresponding increase in hydrogen gas production

Enhancing a solar still's performance by preheating the feed water and employing phase-change material

Drinkable water is becoming increasingly scarce due to increased industrialization and population development, which has forced researchers to come up with new ways to meet this need. Drinkable water can be produced using solar stills, but their output isn't particularly high. A modified solar still (MSS) and a conventional still (CSS) have both been used in an experimental study. The MSS has undergone testing using spiral copper water heating coils (MSS), internal reflector (MSS-IR), and Nano-phase change material (MSS-IR-PCM). The performance of MSS and CSS was tested in three different sets of experiments under identical meteorological conditions. The rise in productivity/thermal efficiency for MSS, MSS-IR, and MSS-IR-PCM are 66%/44%, 81%/46.2% and 115%/51.3%, respectively. The distillate production was increased to be 81% higher than CSS's by adding internal reflector to the MSS's back wall. Therefore, the incorporation of the internal reflector boosted the MSS output by about 15%. It was shown that MSS-IR-PCM is 115% more productive overall than CSS. As a result, utilizing PCM boosted MSS-IR productivity by roughly 34% when compared to the situation without PCM. Economic analysis was also considered. For the CSS and MSS-IR-PCM, the cost of the distilled freshwater is 0.03 and 0.0235 $/L, respectively