Dry Environmental Conditions Research Articles

Influence of environmental relative humidity on the polarization behaviour of paper and paper-dielectric structures

In paper containing multilayer composite structures and laminates, polarization is usually investigated under dry environmental conditions. The aim of this research is to determine polarization dependence of paper and paper-dielectric structures on environmental relative humidity (RH). The role of each component was identified. The obtained and recorded data are used for identification and clarification of the physical mechanism of polarization. The polarization was studied by applying a dosed charging and forced discharge method and was evaluated by a depolarization potential and its formation kinetics. The polarization level of investigated structures increases with RH and is determined mainly by the paper (cellulose) and moisture content in it. In composite structures of the paper between dielectric films and dielectric on paper the polarization dependence on RH correlates with moisture absorption isotherm. It was found that the surface electrical conductivity of paper distorts the results of the paper and structure paper on dielectric. Analysis of the formation kinetics of the depolarization potential together with the potential decay of the charged paper has determined the role of orientation polarization and space charges. The formation of space charges is faster than orientation polarization and dominates in polarization process at higher RH. The process modeling by superposition of two exponents confirms this polarization mechanism.

Influence of laser wavelength on the modification of friction between 100Cr6 steel and polytetrafluoroethylene by femtosecond laser-induced periodic surface structures

The authors report on surface modification by laser-induced periodic surface structures of different periodicities and modulation depths to modify dry and lubricated tribological properties. Using 220 fs laser pulses in the infrared (λ1=1030nm), visible (λ2=515nm), and ultraviolet (λ3=343nm) spectral regions, the authors periodically structure two-dimensional areas with periodicities in the range between 300 and 950 nm and modulation depths between 30 and 180 nm, respectively. The coefficient of friction is measured by performing a linear reciprocating ball-on-disk test with polytetrafluoroethylene balls on such structured 100Cr6 bearing steel. This configuration reveals a modified friction behavior using load forces between 50 and 1000 mN and a translation speed of 4 mm/s. In general, the results show an increased coefficient of friction in the presence of the applied periodic structures. In particular, in the case of dry environmental conditions, laser-induced periodic surface structures with an increasing spatial period lead to an increase in the coefficient of friction. In addition, for a sliding direction perpendicular to the alignment of the periodic structures, a higher coefficient of friction is found in comparison to a parallel movement. While in the case of lubricated friction, an increased coefficient of friction is also found; yet, it reveals a less pronounced dependency of the sliding direction as compared to dry conditions. For lubricated linear reciprocating movements, the coefficient of friction decreases under increasing load forces, which results in a load depended friction reduction.

OLIGO CHITOSAN TEST IN THE INITIAL BULBIL GROWTH OF ILES-ILES (Amorphophallus muelleri Blume)

Oligo chitosan is a supplement that can increase growth, accelerate flowering, and increase productivity in several types of agricultural crops, rice and horticultural commodities. The findings of this study, encourage the authors, to further test the Oligo chitosan on the initial growth of the bulbs of Iles-iles. It is known, that Iles-iles (Amorphophallus muelleri Blume) or "Porang" is one type of tuber whose life cycle is quite long, has a slow-growing bulbil, especially in the dry season. This growth delay is caused in addition to genetic traits, also dry environmental conditions come into effect, so if entering the rainy season at a certain time span will soon show a good appearance of growth. Bulbil as a planting material, in order to grow immediately, it is necessary to strive to accelerate its growth, one of which is to use Oligo chitosan. In the cultivation of iles-iles the use of Oligo chitosan to accelerate bulbil growth has never been done. Technological innovations produced by BATAN, have the opportunity to be used in the development of crop cultivation made from tubers. This study aims to test Oligo chitosan to encourage the realization of early growth of bulbil, through the treatment of immersion time and the concentration of Oligo chitosan which is higher than previous experiments that the authors have done. The experiment was conducted in the rainy season of 2019/2020 in the experimental farm of the UPN "Veteran" Yogyakarta Wedomartani Faculty of Agriculture under a tree stand, using a Split Plot Randomized Completely Block Design (RCBD) with three replications. As the main plot is the soaking time of Oligo chitosan solution, consisting of three kinds, namely 2.5 hours (L1), 5 hours (L2), and 7.5 Hours (L3), and as a sub plot is the concentration of the solution consists of 3 stages, namely (5.0 ‰ (K1), 10 ‰ (K2), and 15 ‰ (K3) and one control (without Oligo chitosan). The data obtained were analyzed by Variance Analysis with 95% confidence level, and for the difference test the Duncan Multiple Range Test (DMRT) was used at the 5% level and the Orthogonal Contrast Test The results showed that soaking Oligo chitosan for 2.5 hours (L1) was sufficient to provide a better initial growth effect for Ilesiles bulbil, with a fairly high concentration of 15 ‰ (K3).Keywords: Oligochitosan, Iles-iles or Porang, bulbil, soaking and concentration

Al-7075 Malzemenin CNC Frezelenmesinde İşlem Parametrelerinin Yüzey Pürüzlülüğüne ve Kesme Enerjisine Etkisinin Optimizasyonu

In this study, it is intended to determine the most suitable process parameters for surface roughness and cutting energy of the 7075 series aluminum material in dry environment conditions by using Taguchi method in CNC milling. The process parameters were determined as, cutting speed, feed rate and cutting depth and the effects of these parameters on surface roughness, current flow through the grid and the energy consumed were examined. As a result, optimum process parameters were determined and the results were analyzed by graphs. It was observed that the most effective parameter on the surface roughness was the feed rate, while the most effective parameter on the current drawn from the network was the cutting depth. As a result of the experiments, the best surface roughness value was found to be 0.39 µm and the lowest current value was 0.9 A. In addition, considering the determined current amount and processing time, the lowest energy amount consumed was calculated as 7089.28 J.

<p><strong>A new species of <em>Limonium</em> from Tunisia</strong></p>

Limonium steppicum, a new species is described and illustrated from the Island of Djerba in Tunisia, where it is localized at the edges of salt marshes in very dry environmental conditions. Morphologically, it is closely related to L. rubescens, widespread in southern Tunisia, from which it is differentiated in many morphological features and also for its ecological requirements.

Dry Bean [Phaseolus vulgaris L.] Growth and Yield Response to Variable Irrigation in the Arid to Semi-Arid Climate

Understanding the crop growth and yield response to variable irrigation and the relationship between crop eco-physiological and morphological parameters is critical for identifying a balanced irrigation management strategy and developing decision support systems for early detection and information for on-ground decisions. Experiments were conducted to evaluate the effect of variable irrigation treatments on dry bean [Phaseolus vulgaris L.] growth traits (plant height, leaf area index, normalized difference vegetation index), seed yield (SY), and yield components (pods plant−1, seeds pod−1, 100-seed weight (SW), and pod harvest index (PHI)) and to develop empirical models between dry bean growth and environmental conditions, SY, and yield components. Five irrigation treatments i.e., FIT (full irrigation treatment), 125% FIT, 75% FIT, 50% FIT, and 25% FIT were investigated. Water deficit at the beginning of the crop growth [vegetative growth (V1-V2) stage], dramatically reduced dry bean growth and development and resulted in a significant reduction in SY. However, the degree to which vegetative growth and SY was reduced depends on the weather conditions. Reducing irrigation by 25% below FIT resulted in an average reduction of 30% in SY. This reduction in SY was significantly correlated with a decline in pods plant−1 and SW. Moreover, the empirical models between growth traits and growing degree days (GDD) have a strong correlation, while growth traits and SY and yield components are moderately correlated. The data and empirical models presented in this research provide valuable information in predicting and estimating dry bean SY in-season and allow for corrective management decisions.

The Role of Nest Depth and Site Choice in Mitigating the Effects of Climate Change on an Oviparous Reptile

Climate change is likely to have strong impacts on oviparous animals with minimal parental care, because nest temperature can impact egg development, sex, and survival, especially in the absence of mitigation via parental care. Nesting females may compensate for increasing temperatures by altering how, when, and where they nest. We examined the factors determining nest depth and site choice as well as the effects that nest depth and location have on nest temperature and hatching success in the diamondback terrapin (Malaclemys terrapin). We found that nest depth was not correlated with nesting female size, egg characteristics, or daily temperatures. Nest temperatures and hatching success were correlated with different environmental and nest characteristics between 2004, a cool and wet year, and 2005, a hot and dry year. Females selected nests with lower southern overstory vegetation in 2005. These results suggest that nest depth and location can play an important yet varying role in determining nest temperature and hatching success in more extreme warm and dry environmental conditions and, therefore, may mitigate the impacts of climate change on oviparous reptiles. However, we found minimal evidence that turtles choose nest locations and depths that maximize offspring survival based on short-term environmental cues.

The Effect of Irrigation Treatment on the Growth of Lavender Species in an Extensive Green Roof System

In green roofs, the use of plant species that withstand dry arid environmental conditions and have reduced water requirements is recommended. The current study presents the effect of irrigation amount on the growth of four different species of lavender; Lavandula angustifolia, Lavandula dentata var. candicans, Lavandula dentata var. dentata, and Lavandula stoechas established on an extensive green roof system and used in urban agriculture. Two irrigation treatments (high and low) determined by the substrate hydraulic properties were applied. Plant growth studied at regular intervals included measurements of plant height, shoot canopy diameter, plant growth index, shoot dry weight and stomatal conductance. The results were consistent and showed that low irrigation reduced plant growth. With the exception of L. stoechas, the appearance of plants watered with the low irrigation treatment was satisfactory, and their use under low water amount irrigation is supported. Interspecies differences among lavender species were present in both irrigation treatments. Overall, L. dentata var. candicans showed the greatest growth, followed in descending order by L. dentata var. dentata and L. angustifolia. In parallel, for stomatal conductance, L. dentata var. candicans showed the lowest value, similar to L. dentata var. dentata, and L. angustifolia the largest. Differences in plant characteristics and size among the latter three species can be considered in the design of extensive green roof systems. The use of substrate hydraulic properties was shown to be important for irrigation management on extensive green roof systems.

Do non-metallic material and radiation shields affect the operation of direct evaporative cooling systems?

The evaporation phenomenon is used as a passive cooling approach to absorb the sensible heat and convert it into the latent heat. The usage of evaporative cooling systems has boomed, recently, because of its low operational cost. The Direct Evaporative Cooling (DEC) systems can be used widely in warm dry environmental conditions, such as Middle East countries. Several factors can affect the DEC system such as water temperature, evaporative cooling pad thickness, air velocity, and solar radiation flux. In this study, the performance and water consumption of evaporative-based cooler manufactured by RFX Polycarbonate-Structured Sheet (PSS) are compared with the metal-casing one. The impacts of tilting the roof of the cooler and attaching a glass wool-aluminum foil on the cooler are evaluated. The assessments show about 20.6% reduction in the usage of water for the case of RFX Polycarbonate-Casing cooler compared to the metallic material. Results also revealed that tilting the roof saves 29% water compared with the metal-casing cooler while changing the inclined roof to the glass wool-aluminum foil radiation shield further saves the water by about 25%. The performance of the RFX-PSS cooler is enhanced by about 4.7% as compared to the metal-casing cooler. The improvement of 8.1% occurs by tilting the roof in RFX Polycarbonate-Casing cooler in comparison with the metallic DEC system and attaching the isolation foil of glass wool-aluminum instead of the inclined roof increases the saturation efficiency by 7%.

Biomolecular Evidence of Early Human Occupation of a High-Altitude Site in Western Central Asia During the Holocene

Reconstructions of early human occupation of high-altitude sites in Central Asia and possible migration routes during the Holocene are limited due to restricted archaeological sample material. Consequently, there is a growing interest in alternative approaches to investigate past anthropogenic activity in this area. In this study, fecal biomarkers preserved in lake sediments from Lake Chatyr Kol (Tian Shan, Kyrgyzstan) were analyzed to reconstruct the local presence of humans and pastoral animals in this low-human-impact area in the past. Spanning the last ~11,700 years, this high-altitude site (~3,500 m above sea level) provides a continuous record of human occupancy in Western Central Asia. An early increase of human presence in the area during the mid-Holocene is marked by a sharp peak of the human fecal sterol coprostanol and its epimer epicoprostanol in the sediments. An associated increase in 5β-stigmastanol, a fecal biomarker deriving from herbivores indicates a human occupancy that most probably largely depended upon livestock. However, sterol profiles show that grazing animals had already occupied the catchment area of Lake Chatyr Kol before and also after a significant presence of humans. The biomarker evidence in this study demonstrates an early presence of humans in a high-altitude site in Central Asia at ~5,900 - 4,000 a BP. Dry environmental conditions during this period likely made high altitude regions more accessible. Moreover, our results help to understand human migration in Western Central Asia during the early and mid-Holocene as part of a prehistoric Silk Road territory.

Fertility of the male gametes of Lagerstroemia indica L. by different coloring methods

The Lagerstroemia indica L. is a representative of the family Lythraceae, is popularly known as extreme, resedá rosa or madness. It is a small tree with dense and deciduous canopy, measuring from 2 to 4m high, resistant to dry climate and environmental conditions of cities. The present work aimed to evaluate the pollen feasibility of the Lagerstroemia indica L., through the dyes of 1% Green Malignant, Lugol 2% and Alexander Reactive and 2,3,5 Triphenyl tetrazolium chloride (TTC) at the dilutions of 0.075% and 0.030%. In order to verify the pollen fertility, we used closed flowers from three populations of Lagerstroemia indica L., following the methodology of Guerra & Souza (2002), submitting the treatments. In the application of the TTC dye, anthers of fresh buds were arranged in two concentrations: 0.075% and 0.30%, being evaluated in the periods of 6:00 a.m., 12:00 a.m., 6:00 p.m. and 24:00 a.m. The use of R. dyes from Alexander, V. Malachite 1% and Lugol 2% and from TTC to determine pollen feasibility proved to be efficient in differentiating the fertile and infertile pollen from the species. In the use of TTC it is recommended to use in the 0.30% solution during 12h of fixation of the pollen granules, period in which a higher coloring average was obtained.

Geochemical study of the vertebrate assemblage zones of the Santa Maria Supersequence (Middle to Late Triassic), Paraná Basin, Brazil

The Middle-Upper Triassic section of the Paraná Basin is included in the Santa Maria Supersequence. This stratigraphic unit is classified as a second-order Supersequence, being subdivided into three third-order sequences in which four Assemblage Zones (AZ) based on tetrapods are recognized. In this work, chemical analyses of fossils and hosting rocks of each AZ were performed in order to verify whether the geochemical patterns of the rocks could serve to distinguish them even in the absence of fossils. For this purpose, nine samples of fossils and their sedimentary matrices were analyzed, by ICP-MS. The results show that there were changes in the chemical parameters in force at the depositional time of each sequence (and corresponding AZ). In general, the lower portion of the package was deposited under more basic and dry environmental conditions, indicated by the Ca and Ba concentrations found in the rocks and bones that contains them. By its turn, the top of the section is characterized by more acid and humid conditions, evidenced by Al, Si, and Sr increase. Such a geochemical shift from dry to humid conditions occurred just at the beginning of the Late Triassic and is probably related to the Carnian Pluvial Episode.

EXPERIMENTAL INVESTIGATIONS OF EVAPORATIVE COOLING SYSTEM FOR BUILDINGS UNDER HOT AND DRY ENVIRONMENTAL CONDITIONS

The performance of one-stage direct evaporative cooler (DEC) and two-stage indirect-direct evaporative cooler (IEC−DEC) in the environment of Saudi Arabia is assessed experimentally. The wet pad used in direct evaporative coolers is one of the main parts affecting the output of an evaporative cooler. In this study, three combinations of pad materials: a combination of aspen fiber and corrugated cellulose (Case-I), corrugated cellulose (Case-II), and aspen fiber (Case-III) were focused as a wet media for water evaporation and the performance of these pad materials was analyzed in detail. The main design parameter considered is the water fl ow rate in the designing of both coolers. During the testing of both coolers the ambient temperature in the range from 28°C to 42°C and relative humidity lower than 65% were considered to cool the working air. The air temperature and relative humidity were measured and the eff ectiveness of the coolers was determined. The results obtained show that eff ectiveness of the IEC−DEC system is in range of 95−110%, while that of DEC amounts to 85−93%. As an overall the IEC−DEC system with pad material of Case-I showed a comparatively better performance.

Tribological studies of EN31 steel and Ti-6Al-4V alloy materials using pin-on-disc tribometer

Mechanical parts in modern machining systems are often subjected to friction and wear causing high heat generation at the contact zones leading to reduced lifecycle and increased power consumption of machinery. Coolants, despite controlling this high contact zone heat, are uneconomical due to their high cost. Various researchers across industries have been focusing towards replacing coolants by developing newer lubricants to obtain environmental and economic benefits. The current work presents an experimental investigation to evaluate tribological characteristics of bearing steel (EN 31) and Ti-6Al-4V alloy using MoS2 as solid lubricants. Friction and wear properties were measured on a pin-on-disc tribometer at different sliding conditions. Solid lubricant was effectively supplied to the pin-disc interface zone through a specially designed experimental set-up namely minimum quantity solid lubricant (MQSL). The obtained results are compared with the dry and wet environmental conditions. The results indicate a significant improvement in the tribological performance of steel and alloy materials under MQSL when compared with dry and wet environment conditions. The work presented here provides a good understanding of methods to cool/lubricate the sliding zones, reduce temperature at sliding interface to make the machining of difficult-to-cut materials more efficient and economic.

Accelerated Wound Healing by a Topical Wound Healing Lipogel in Patients Undergoing Catheter De-placement - Evidence from a Randomized, Controlled Clinical Study

Objective: The purpose of this clinical study was to assess a novel wound model and to compare the wound healing properties of a topical wound healing hydroactive lipogel (MediGel®) promoting moist wound environment versus standard treatment by a standard plaster und dry environmental conditions in patients undergoing catheter de-placement as a model for non-acute wounds affecting all skin layers in real life conditions (moist environment does improve granulation & epithelialization supported by Lipogel – the MEDIGEL trial). Methods: Patients (n=69) admitted to the dialysis ward of a tertiary care institution with acute or chronic renal insufficiency and in need for dialysis were enrolled into a prospective, observer-blind, randomized, controlled, inter-individual experimental comparison study. Patients enrolled were undergoing placement of Sheldon multi-lumen catheter (11 French diameter) in the external jugular vein at the neck by Seldinger technique to enable access for hemodialysis. One group of patients which had catheter displaced after one session of hemodialysis was regarded as acute wound group. A different group of patients had catheter withdrawn after 14 (+/- 2 days) and was classified as non-acute wound group. Topical treatments were randomly allocated, i.e. traditional care with standard plaster (control group) or investigational product (promoting moist environment) beneath a standard plaster (investigational product). Wound healing was assessed (digital photography, visual scoring) and analyzed via comparison of area under curve at day 0, 3 and 7 after displacement of catheter. Results: Evaluation showed significantly faster wound healing results for the investigational product in comparison to standard (all time points) and with significant AUC difference in both patient groups, acute and non-acute. Visible re-epithelialization was recorded from day 3 to day 7 in acute wounds, delayed in non-acute wounds. Standard plaster-treated wounds remained open and had markedly larger wound area. Formation of fibrous scar tissue was minimal but less prominent in patients treated with the hydroactive lipogel in the non-acute group due to faster epithelialization promoted by moist environment. Conclusion: Clinically relevant accelerated epithelialization and faster wound healing were observed for the investigational product compared to traditional treatment indicating superiority of moist wound environmental conditions both in acute and non-acute wounds after displacement of catheter placed into the jugular vein for 5 hours or 2 weeks in patients undergoing hemodialysis. The model is an innovative approach to study acute and non-acute wounds affecting all three skin layers and should be further investigated.

U-Pb zircon geochronology of high-grade charnockites– exploration of pre-Mesoproterozoic crustin the Mazury Complex area

Charnockites – i.e., orthopyroxene-bearing felsic rocks – were formed in a deep-seated dry environment, either under plutonic or high-grade metamorphic conditions. Most charnockites known from the crystalline basement of Poland appear to be of Mesoproterozoic age (1.50–1.54 Ga), cogenetic with the Suwałki Anorthosite Massif, and associated with mangerite and granite members forming the AMCG suite of the Mazury Complex. Genetically distinct rocks, characterised by the presence of anhydrous minerals, e.g., orthopyroxene and garnet, were also recognised along 592 m of the Łanowicze PIG-1 borehole section, within the AMCG suite. U-Pb geochronology by sensitive high resolution ion microprobe (SHRIMP) was used to date the complexly zoned zircons. The ages of crystallisation of the charnockite protoliths from various depths at 1837±7, 1850±9, 1842±6, and 1881±16 Ma makes these rocks the oldest dated crust within this part of the Polish basement. The Łanowicze PIG-1 borehole section bears components from neighbouring tectonic domains known from Lithuania: the West and Middle Lithuanian (WL/MLD) domains considered as a continental margin at 1.84–1.86 Ga and the fragmented Latvia-East Lithuania (LEL) domain, where the oldest continental crust was generated at c. 1.89– 1.87 Ga. The metamorphic zircon overgrowths document a high-grade event at 1.79 Ga and then constrained at 1.5 Ga. Dating of pre-Mesoproterozoic crust cryptic within the AMCG Mazury Complex provides valuable information on the nature of the pre-existing blocks formed during the long lasting Svecofennian orogeny.

Rhizosphere Metagenomics of Paspalum scrobiculatum L. (Kodo Millet) Reveals Rhizobiome Multifunctionalities.

Multifunctionalities linked with the microbial communities associated with the millet crop rhizosphere has remained unexplored. In this study, we are analyzing microbial communities inhabiting rhizosphere of kodo millet and their associated functions and its impact over plant growth and survival. Metagenomics of Paspalum scrobiculatum L.(kodo millet) rhizopshere revealed taxonomic communities with functional capabilities linked to support growth and development of the plants under nutrient-deprived, semi-arid and dry biotic conditions. Among 65 taxonomically diverse phyla identified in the rhizobiome, Actinobacteria were the most abundant followed by the Proteobacteria. Functions identified for different genes/proteins led to revelations that multifunctional rhizobiome performs several metabolic functions including carbon fixation, nitrogen, phosphorus, sulfur, iron and aromatic compound metabolism, stress response, secondary metabolite synthesis and virulence, disease, and defense. Abundance of genes linked with N, P, S, Fe and aromatic compound metabolism and phytohormone synthesis—along with other prominent functions—clearly justifies growth, development, and survival of the plants under nutrient deprived dry environment conditions. The dominance of actinobacteria, the known antibiotic producing communities shows that the kodo rhizobiome possesses metabolic capabilities to defend themselves against biotic stresses. The study opens avenues to revisit multi-functionalities of the crop rhizosphere for establishing link between taxonomic abundance and targeted functions that help plant growth and development in stressed and nutrient deprived soil conditions. It further helps in understanding the role of rhizosphere microbiome in adaptation and survival of plants in harsh abiotic conditions.

Decreased nest survival associated with low temperatures in a high-elevation population of Mountain Plover (Charadrius montanus)

Mountain Plovers (Charadrius montanus) are migratory shorebirds of conservation concern that breed on grasslands and xeric tablelands scattered along the western edge of the Great Plains. Previous research from populations breeding on lower-elevation sites in Colorado and Montana suggests nest survival increases in cooler, drier environmental conditions. However, no studies have estimated Mountain Plover nest survival on high-elevation habitats, which have distinctively different climate and nesting phenology; therefore, it is unclear if these general trends hold true for the species as a whole or are regionally specific. In this study, we monitored nests of a population of Mountain Plovers breeding at high elevation in South Park, Colorado, to study influences on daily nest survival as compared to those found in literature from lower-elevation breeding sites. In contrast to studies on lower-elevation sites where daily maximum temperatures limited nest survival, we found daily minimum temperature best predicted variation in daily nest survival in South Park; survival odds declined with decreasing temperature. These results suggest that negative effects of extreme temperatures (hot or cold) may be generalities that exist between locales but are potentially mediated through different mechanisms at varying temporal scales. Although we cannot definitively conclude from our study why minimum temperature is associated with lower nest survival, we suggest alterations in incubation behavior may be a plausible mechanism that warrants future study. Overall, our study demonstrates the importance of considering differences between weather and phenology among breeding locations when estimating nest survival effects.

Oak Savannas in Western New York State, Circa 1795: Synthesizing Predictive Spatial Models and Historical Accounts to Understand Environmental and Native American Influences

This study models and maps oak savanna distribution ca. 1795 and determines how environmental conditions and Native American land use (NALU) shaped its distribution. Historical research has analyzed early landscape accounts to assess how Native Americans modified forests throughout the eastern United States. Predictive spatial modeling has sought to quantify anthropogenic and environmental drivers of forest conditions and to predict locations where NALU changed forest composition. Yet, studies have not rigorously synthesized these two methods. This research focused on oak savannas in western New York State (27,617 km2). We trained models of oak savanna distribution from historic vegetation data in relation to environmental predictors and NALU proxies. We then mapped historical accounts of oak savannas and NALU at European-American arrival and compared them to model predictions. Results suggest that 2 to 17 percent (depending on modeling technique) of the study area contained oak savanna, with a favored estimate of 3 to 6 percent. Synthesis of models and accounts suggests that oak savannas were attributable to NALU and dry environmental conditions but that NALU (specifically burning) was present at most oak savanna locations. Models of oak savanna distribution that considered proximity to Native American settlement had higher predictive performance and better predicted locations of historical oak savanna accounts, including those with descriptions of Native American burning. This study suggests that former oak savannas in the study area can be largely attributed to NALU. Furthermore, this study’s methodology and results contribute to a larger body of geographical literature on savanna landscapes. Key Words: anthropogenic burning, forests, modeling, Native Americans, oak savanna.

Effect of Machining Parameters on Tool Wear and Surface Roughness In Dry and Wet Machining of Aisi 316 Austenitic Stainless Steel by Taguchi Method

Stainless steels are widely used to manufacture mechanical components due to excellent mechanical properties. Machining is considered as one of the most critical manufacturing processes in mechanical industry to produce desired shapes and dimensional accuracy of the components. It also affects the performance of the components in its functional requirement. This paper deals with the optimization of cutting parameters in machining operation for AISI 316 austenitic steel with dry and wet environment conditions. The chosen machining parameters in this research are cutting speed, feed rate, and depth of cut as input variables, whereas the response factors are surface roughness and wear rate. Taguchi method with the L9 orthogonal array was used to analyze the process parameters based in dry and wet machining conditions. The Taguchi approach provides the best setting with lower values of surface roughness and wear rate. The regression analysis is performed to obtain a mathematical model of responses in terms of the process parameter. The composite regression optimization gives best setting for dry condition (cutting speed 173 rpm, feed 0.25 mm/rev, and 0.87 mm of the depth of cut) and for wet condition (cutting speed 173 rpm, feed 0.3 mm/rev, and 0.57 mm of the depth of cut). The results show that surface roughness and wear rate are lower in the wet environment than the dry environment.