Derivation of a poroelastic flexural shell model

In this paper we investigate the limit behavior of the solution to quasi-static Biot's equations in thin poroelastic flexural shells as the thickness of the shell tends to zero and extend the results obtained for the poroelastic plate by Marciniak-Czochra and Mikeli\'c. We choose Terzaghi's time corresponding to the shell thickness and obtain the strong convergence of the three-dimensional solid displacement, fluid pressure and total poroelastic stress to the solution of the new class of shell equations. The derived bending equation is coupled with the pressure equation and it contains the bending moment due to the variation in pore pressure across the shell thickness. The effective pressure equation is parabolic only in the normal direction. As additional terms it contains the time derivative of the middle-surface flexural strain. Derivation of the model presents an extension of the results on the derivation of classical linear elastic shells by Ciarlet and collaborators to the poroelastic shells case. The new technical points include determination of the 2 X 2 strain matrix, independent of the vertical direction, in the limit of the rescaled strains and identification of the pressure equation. This term is not necessary to be determined in order to derive the classical flexural shell model.Comment: 32 page

Energy Efficiency and Renewable Energy Management with Multi-State Power-Down Systems

A power-down system has an on-state, an off-state, and a finite or infinite number of intermediate states. In the off-state, the system uses no energy and in the on-state energy it is used fully. Intermediate states consume only some fraction of energy but switching back to the on-state comes at a cost. Previous work has mainly focused on asymptotic results for systems with a large number of states. In contrast, the authors study problems with a few states as well as systems with one continuous state. Such systems play a role in energy-efficiency for information technology but are especially important in the management of renewable energy. The authors analyze power-down problems in the framework of online competitive analysis as to obtain performance guarantees in the absence of reliable forecasting. In a discrete case, the authors give detailed results for the case of three and five states, which corresponds to a system with on-off states and three additional intermediate states “power save”, “suspend”, and “hibernate”. The authors use a novel balancing technique to obtain optimally competitive solutions. With this, the authors show that the overall best competitive ratio for three-state systems is 95 role= presentation style= box-sizing: border-box; max-height: none; display: inline; line-height: normal; text-align: left; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3e95 and the authors obtain optimal ratios for various five state systems. For the continuous case, the authors develop various strategies, namely linear, optimal-following, progressive and exponential. The authors show that the best competitive strategies are those that follow the offline schedule in an accelerated manner. Strategy “progressive” consistently produces competitive ratios significantly better than 2

Unified Models of Inflation and Quintessence

We apply an extended version of the method developed in reference Int.J.Mod.Phys.D5(1996)71, to derive exact cosmological (flat) Friedmann-Robertson-Walker solutions in RS2 brane models with a perfect fluid of ordinary matter plus a scalar field fluid trapped on the brane. We found new exact solutions, that can serve to unify inflation and quintessence in a common theoretical framework.Comment: 8 pages, no figure

Open Data Platform for Knowledge Access in Plant Health Domain : VESPA Mining

Important data are locked in ancient literature. It would be uneconomic to produce these data again and today or to extract them without the help of text mining technologies. Vespa is a text mining project whose aim is to extract data on pest and crops interactions, to model and predict attacks on crops, and to reduce the use of pesticides. A few attempts proposed an agricultural information access. Another originality of our work is to parse documents with a dependency of the document architecture

Asymptotic analysis of the Poisson-Boltzmann equation describing electrokinetics in porous media

We consider the Poisson-Boltzmann equation in a periodic cell, representative of a porous medium. It is a model for the electrostatic distribution of $N$ chemical species diluted in a liquid at rest, occupying the pore space with charged solid boundaries. We study the asymptotic behavior of its solution depending on a parameter $\beta$ which is the square of the ratio between a characteristic pore length and the Debye length. For small $\beta$ we identify the limit problem which is still a nonlinear Poisson equation involving only one species with maximal valence, opposite to the average of the given surface charge density. This result justifies the {\it Donnan effect}, observing that the ions for which the charge is the one of the solid phase are expelled from the pores. For large $\beta$ we prove that the solution behaves like a boundary layer near the pore walls and is constant far away in the bulk. Our analysis is valid for Neumann boundary conditions (namely for imposed surface charge densities) and establishes rigorously that solid interfaces are uncoupled from the bulk fluid, so that the simplified additive theories, such as the one of the popular Derjaguin, Landau, Verwey and Overbeek (DLVO) approach, can be used. We show that the asymptotic behavior is completely different in the case of Dirichlet boundary conditions (namely for imposed surface potential)

Walking Speed: A Factor in the Physical Fitness of the Elderly

The main purpose of the study was to explore whether gait velocity predicts the  level of separate and overall physical fitness. In this study, we asked one hundred and twenty older adults over the age of 60 (mean ± SD age 71 ± 7 38 years, height 159 ± 21 cm, weight 70 ± 13 kg) to complete a Senior Fitness Test battery to assess the level of physical fitness and walked across the Zebris pressure platform (Munich, Germany) to measure gait velocity. To calculate overall physical fitness, we summed z-score values of each physical fitness test. Pearson’s coefficient (r) was used to determine the level of correlation and coefficient of determination (r2) for variance explained between gait velocity and physical fitness. Respondents conducted a battery of six tests: “chair stand in 30 s”, “arm curl in 30 s”, “2–minute step test”, “chair sit-and-reach test”, “back scratch test” and “8-feet up-and-go test”. Gait velocity was significantly correlated with chair stand in 30 sec (r=0.45, r2=20%,  p<0.001), arm curl in 30 sec (r=0.56, r2=31%, p<0.001), 2-minute step test (r=0.44, r2=19%,  p<0.001), chair sit-and-reach test (r=0.46, r2=21%, p<0.001), back scratch test (r=0.30,  r2=9%, p<0.001) and 8-feet up-and-go test (r=-0.23, r2=5%, p=0.011). Gait velocity was not significantly correlated with waist circumference (r=0.12, r2=1%, p=0.189). Overall physical fitness was strongly correlated with gait velocity (r=0.75, r2=56%, p<0.001). In conclusion this study shows that gait velocity may be an easy and quick screening tool to predict the level of separate and overall physical fitness in a sample of older adults.   Keywords: elderly, speed, performance, correlation, too

ANALISA PENGARUH MIGRASI WARGA TRANSMIGRASI TERHADAP MASYARAKAT DESA SITUGAL KECAMATAN LOGAS TANAH DARAT

Desa Situgal memiliki banyak lahan kosong dan hutan yang berpotensi menjadi perkebunan  yang berada di Desa Situgal Kecamatan Logas Tanah Darat. Pada Tahun 2004 awal masuknya masyarakat ekstrans migrasi ke Desa Situgal dengan membeli lahan kosong, hutan maupun perkebunan karet yang selanjunya diolah menjadi perkebunan sawit. Pengaruh masyarakat ekstransmirasi terhadap masyarakat setempat di Desa Situgal yaitu terhadap Sosial ,Ekonomi dan Fisik Desa Situgal Kecamatan Logas Tanah Darat Kabupaten Kuantan Singingi. Adapun tujuan penelitian untuk mengetahui bagaimana pengaruh adanya migrasi warga transmigrasi terhadap perubahan Sosial, Ekonomi dan kondisi fisik (infrastruktur) serta pola guna lahan Desa Situgal Kecamatan Logas Tanah Darat. Menggunakan Metode penelitian deskriptif kualitatif mendeskripsikan kondisi pengaruh masyarakat ekstransmigrasi terhadap masyarakat setempat di Desa Situgal berdasarkan observasi langsung, wawancara narasumber dari instansi pemerintahan terkait dan tokoh masyarakat. Berdasarkan hasil analisis dan pembahasan penelitian, hasil penelitian yang didapat yaitu terindikasinya masyarakat Desa Situgal menemukan Budaya baru yang dibawa masyarakat Ekstransmigrasi, terciptanya permukiman baru, perkabunan kelapa sawit dan penambahan prasarana jalan. Namun terdapat juga pengaruh negatif dibeberapa faktor seperti lahan Desa Situgal yang terbatas ditambah lagi sudah banyak dijual kepada masyarakat ektransmigrasi sehingga sedikitnya lahan perkebunan yang dimiliki masyarakat setempat yang menyebabkan lahan perkebunan yang semakin menipis adanya kejadian tindak criminal seperti pencurian namun dari segi lapangan pekerjaan meningkat karena banyaknya lapangan pekerjaan bar

Open-Source Research and Mapping of Explosive Ordnance Contamination in Ukraine

Due to Russia’s full-scale invasion of Ukraine, the scale of explosive ordnance (EO) contamination in Ukraine has reached unprecedented levels, necessitating new methods to assess and track the different types of ordnance and the level of contamination across the country. As the most documented, active war on social media to date, The HALO Trust (HALO) has successfully harnessed open-source research to better plan and conduct survey, clearance operations, and explosive ordnance risk education (EORE) across the country