Influence of different types of AGM separators on parameters of lead-acid batteries for hybrid electric vehicles

Nejpoužívanějším sekundárním zdrojem je v dnešní době olověný akumulátor. Svoje využití nachází i jako pohon v hybridních elektrických vozidlech. Princip zůstává stejný od vzniku, ale jsou stále vylepšovány jeho parametry. Životnost akumulátoru ovlivňuje mimo jiné i použitý separátor. Práce se zabývá popisem vlastností separátorů olověných akumulátorů, způsoby jejich testování a vyhodnocení vhodnosti použití.The most used type of the secondary energy sources is the lead-acid accumulator today. It is also used as a propulsion in hybrid electric vehicles. Functional principle stayed same as in foundation time, only parameters are still improving. Lifetime of lead-acid accumulator is influenced by used separator. The work deals with the description of properties of lead acid separators, methods of testing and evaluation of the suitability for use.

Spike Serve In Cadet Volleyball Players

Cílem studie bylo zjistit vztah rychlosti smečovaného podání, dosahem při kontaktu s míčem a modelovou výškou výskoku jako ukazatele explozivní síly dolních končetin, a tyto hodnoty vzájemně korelovat. Sledovaná skupina byla složen a ze 169 hráčů (n = 172, věk 15,95±0,75 roku, tělesná výška 185,44±6,9 cm, tělesná hmotnost 71,92±7,92 kg). Hráči absolvovali před měřením test výskoku, kdy se v modelové situaci snažili po rozběhu docílit maximální výšky výskoku. Průměrná rychlost podání byla 79,4 ± 9,4 km.h-1. Nejrychlejší podání mělo hodnotu 105,9 km.h-1, nejpomalejší 56,3 km.h-1 (rozdíl 46,8 %). Ze získaných maximálních hodnot byly vytvořeny procentilové normy (padesátý percentil P50 = 79,9 km.h-1). Procentilové rozložení pro rychlosti smečovaného podání a výskoku umožňuje vzhledem k relativně vysokému počtu naměřených hráčů vzít uvedené hodnoty jako normativní, a porovnávat tak další hráče. Ukazuje se, že korelace výšky výskoku je dobrým ukazatelem dispozice k realizaci smečovaného podání vzhledem k dosažené rychlosti míče.The aim of the study was to determine the relationship between jump serve velocity achieved in contact with the ball and a model height of the jump as an indicator of explosive strength of lower extremities and to correlate these values. The monitored group consisted of 169 players (n = 172, age 15.95 ± 0.75-year, body height 185.44 ± 6.9 cm, body weight 71.92 ± 7.92 kg). Before the measurement, the players undertook a jump test, then, in a model situation, they attempted to achieve maximum jump height after a run-up. The highest serve velocity value was 105.9 km.h-1, while the lowest value was 56.3 km.h-1 (difference by 46.8 %). The measured maximum values were converted into percentile norms (50th percentile P50 = 79.9 km.h1). Percentile distribution for jump serve velocity and the jump enables us, (with respect to a relatively high number of tested players), to consider the stated values as normative and to compare other players, as well. It appears that the correlation of jump height is a good indicator of the dispositions for jump serve implementation in terms of the ball velocity

Kinematic Analysis Of Attack Hit Of Inside Attacker´S Volleyball Players

Cílem práce bylo porovnání a následné vyhodnocení útočného úderu středem sítě (zóna 3) v různých variantách provedení. Pro popis a vyhodnocení kinematiky pohybu byla použita metoda 3D kinematické analýzy. Sledovanou skupinou bylo 6 hráčů extraligové úrovně ve volejbalu mužů. Výsledkem analýzy byla deskripce jednotlivých fází a klíčových okamžiků techniky provedení. Dílčím cílem práce bylo prokázat vysokou intraindividuální stabilitu provedení jednotlivých hráčů vrcholové úrovně. Všichni sledovaní hráči prováděli útočný úder v modelové situaci vícekrát po sobě a pro analýzu byly subjektivně vybrány tři pokusy od každého hráče. Prokázalo se, že hráči vrcholové úrovně provádějící stejnou techniku mají vysokou interindividuální stabilitu provedení v klíčových fázích a momentech. Naměřené výsledky naznačují, že realizace uvedené herní činnosti vyžaduje vysoký stupeň součinnosti útočícího a nahrávajícího hráče.The aim of the work was to compare and subsequently evaluate an offensive attack on a volleyball court (zone 3) in various positions. The method of 3D cinematic analysis was used to describe and evaluate the kinematics of motion. The monitored group was 6 players of the extra-league level in men's volleyball. The result of the analysis was a description of the individual phases and key moments of the technique. The partial goal of the work was to demonstrate the high intra-individual stability of the execution of individual top-level players. All monitored players performed an offensive shot in the model situation several times in a row, and three attempts from each player were subjectively selected for analysis. Top-level players performing the same technique have been shown to have high inter-individual performance stability at key stages and moments. The measured results indicate that the implementation of this game activity requires a high degree of cooperation between the attacking and recording player

Identification And Comparison Of Body Composition In Elite Judo Players

Hydrodenzitometriou sme zistili u vrcholových judistov vysoké množstvo aktívnej hmoty a veľmi nízke zastúpenie tukového tkaniva. Rozdiel v týchto parametroch bol medzi jednotlivými tímami významný (p<0,05), pričom tím mužov mal lepšie predispozície pre športový výkon ako juniorský tím. Výskum telesného zloženia nie je dôležitý len z hľadiska predikcie výkonu, ale aj pre popis zmien pri predsúťažnom znižovaní hmotnosti. Forma znižovania hmotnosti ako aj hmotnostný limit u daného jednotlivca sú predmetom ďalšieho vyšetrovania. Použitá metóda – hydrodenzitometria – sa ukázala pri eleminácii rušivých faktorov (oscilácia váhy, fáza zaučenia probandov pri výdychu) ako veľmi presný spôsob identifikácie telesného zloženia. Zistené nízke hodnoty tukového tkaniva indikujú potrebu diskusie o použitých predikčných rovniciach pre odhad celkového tuku a aktívnej hmoty v tele a ich prípadných zmenách.The authors present a higher percentage of fat free mass and a lower percentage of fat mass when examined by hydrodensitometry in elite judo athletes. The difference in both indicators of body composition between both examined groups was significant (p<0.05); however, we may see a better predisposition to sport performance in seniors when compared to juniors. The examination of body composition is important in terms of a sport performance predictor, as well as for monitoring changes while reducing weight. The form of reduction and individual limits of body weight remain the matter of further research. The method used was hydrodensitometry, which appears to be a very exact method when disturbing factors, participants learning phase, expiration and scales oscillation are eliminated. The measured low proportion of fat mass indicates a discussion about equations for calculation of total fat mass in the body and their modification and assessment of particular parameters or indicators

Training Workload Influence To Postural Stability Of Junior National Team Pentathletes

Tento příspěvek se zabývá hodnocením vlivu sportovního zatížení na vybrané parametry posturální stability moderních pětibojařů (juniorů n = 7, juniorek n = 5), medailistů z MS a ME juniorů. Měření stability bylo provedeno na stabilometrické desce Footscan před a po zátěži v simulovaných závodních podmínkách. Závěry vyplývající z experimentu: Vliv zátěže na stabilitu širokého stoje nelze za daných podmínek potvrdit (na hladině významnosti α = 0,05). Dosažený výsledek je zřejmě ovlivněn prodlevou mezi zátěží a měřením.The article evaluates the influence of physical exertion on selected postural stability parameters of junior modern pentathletes (7 male athletes, 5 female athletes). Both groups were medallists from the junior world or European championships. Measurements were taken before and after exertion on stabilomethric desk Footscan. Racing conditions were simulated. Conclusions from the experiment were: it was not possible to confirm influence of exertion on wide stand (from statistical point of view – on confidence level α = 0,05). It is assumed the result was influenced by the delay between exertion and measurement

Influence of sampling and disturbance history on climatic sensitivity of temperature-limited conifers

The study was supported by the institutional project MSMT (CZ.02.1.01/0.0/0.0/16_019/0000803) and the Czech Ministry of Education (Project INTER-COST No. LCT17055).Accurately capturing medium- to low-frequency trends in tree-ring data is vital to assessing climatic response and developing robust reconstructions of past climate. Non-climatic disturbance can affect growth trends in tree-ring-width (RW) series and bias climate information obtained from such records. It is important to develop suitable strategies to ensure the development of chronologies that minimize these medium- to low-frequency biases. By performing high density sampling (760 trees) over a ~40-ha natural high-elevation Norway spruce (Picea abies) stand in the Romanian Carpathians, this study assessed the suitability of several sampling strategies for developing chronologies with an optimal climate signal for dendroclimatic purposes. There was a roughly equal probability for chronologies (40 samples each) to express a reasonable (r = 0.3?0.5) to non-existent climate signal. While showing a strong high-frequency response, older/larger trees expressed the weakest overall temperature signal. Although random sampling yielded the most consistent climate signal in all sub-chronologies, the outcome was still sub-optimal. Alternative strategies to optimize the climate signal, including very high replication and principal components analysis, were also unable to minimize this disturbance bias and produce chronologies adequately representing climatic trends, indicating that larger scale disturbances can produce synchronous pervasive disturbance trends that affect a large part of a sampled population. The Curve Intervention Detection (CID) method, used to identify and reduce the influence of disturbance trends in the RW chronologies, considerably improved climate signal representation (from r = 0.28 before correction to r = 0.41 after correction for the full 760 sample chronology over 1909?2009) and represents a potentially important new approach for assessing disturbance impacts on RW chronologies. Blue intensity (BI) also shows promise as a climatically more sensitive variable which, unlike RW, does not appear significantly affected by disturbance. We recommend that studies utilizing RW chronologies to investigate medium- to long-term climatic trends also assess disturbance impact on those series.PostprintPeer reviewe

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Publisher Copyright: © 2022, The Author(s).Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.Peer reviewe

Legacy of pre-disturbance spatial pattern determines early structural diversity following severe disturbance in mountain spruce forests in Czech Republic

Background Severe canopy-removing disturbances are native to many temperate forests and radically alter stand structure, but biotic legacies (surviving elements or patterns) can lend continuity to ecosystem function after such events. Poorly understood is the degree to which the structural complexity of an old-growth forest carries over to the next stand. We asked how predisturbance spatial pattern acts as a legacy to influence post-disturbance stand structure, and how this legacy influences the structural diversity within the early-seral stand. Methods Two stem-mapped one-hectare forest plots in the Czech Republic experienced a severe bark beetle outbreak, thus providing before-and-after data on spatial patterns in live and dead trees, crown projections, down logs, and herb cover. Results Post-disturbance stands were dominated by an advanced regeneration layer present before the disturbance. Both major species, Norway spruce (Picea abies) and rowan (Sorbus aucuparia), were strongly self-aggregated and also clustered to former canopy trees, predisturbance snags, stumps and logs, suggesting positive overstory to understory neighbourhood effects. Thus, although the disturbance dramatically reduced the stand’s height profile with ~100% mortality of the canopy layer, the spatial structure of post-disturbance stands still closely reflected the pre-disturbance structure. The former upper tree layer influenced advanced regeneration through microsite and light limitation. Under formerly dense canopies, regeneration density was high but relatively homogeneous in height; while in former small gaps with greater herb cover, regeneration density was lower but with greater heterogeneity in heights

Jet stream position explains regional anomalies in European beech forest productivity and tree growth.

The mechanistic pathways connecting ocean-atmosphere variability and terrestrial productivity are well-established theoretically, but remain challenging to quantify empirically. Such quantification will greatly improve the assessment and prediction of changes in terrestrial carbon sequestration in response to dynamically induced climatic extremes. The jet stream latitude (JSL) over the North Atlantic-European domain provides a synthetic and robust physical framework that integrates climate variability not accounted for by atmospheric circulation patterns alone. Surface climate impacts of north-south summer JSL displacements are not uniform across Europe, but rather create a northwestern-southeastern dipole in forest productivity and radial-growth anomalies. Summer JSL variability over the eastern North Atlantic-European domain (5-40E) exerts the strongest impact on European beech, inducing anomalies of up to 30% in modelled gross primary productivity and 50% in radial tree growth. The net effects of JSL movements on terrestrial carbon fluxes depend on forest density, carbon stocks, and productivity imbalances across biogeographic regions