1,439 research outputs found
The Deterministic Capacity of Relay Networks with Relay Private Messages
We study the capacity region of a deterministic 4-node network, where 3 nodes
can only communicate via the fourth one. However, the fourth node is not merely
a relay since it can exchange private messages with all other nodes. This
situation resembles the case where a base station relays messages between users
and delivers messages between the backbone system and the users. We assume an
asymmetric scenario where the channel between any two nodes is not reciprocal.
First, an upper bound on the capacity region is obtained based on the notion of
single sided genie. Subsequently, we construct an achievable scheme that
achieves this upper bound using a superposition of broadcasting node 4 messages
and an achievable "detour" scheme for a reduced 3-user relay network.Comment: 3 figures, accepted at ITW 201
Oil Demand, Supply, andMedium-Term Price Prospects:A Wavelets-Based Analysis
The global “great recession” was precipitated in part by record high prices of oil and other commodities. Previous severe recessions have typically resulted in significantly lower energy prices, which in turn spurred growth and fueled a healthy recovery. In part due to expansionary monetary policies worldwide, oil prices have remained relatively high, making it difficult for the global economy to stage a strong recovery. The result is a short-to-medium term forecast of weak to modest growth, which – combined with continuously falling energyintensity of GDP – means that oil demand will remain stagnant or at best grow modestly. Under these circumstances, surging supply from U.S. shale and similar technologically-driven unconventional oil sources is likely to create excess supply and put strong downward pressure on oil prices. Voluntary reduction in oil production to prevent falling prices is highly unlikely, because swing producer Saudi Arabia and other GCC countries need revenues at the level of current volumes and prices in order to meet core budgetary requirements and prevent regime-change risk in the aftermath of “Arab Spring” revolts. Our wavelet analysis of all countries that have ever produced more than one million barrels of oil per day shows that regime change by itself would not result in significant reduction in oil production – although it may result in lower investment and therefore prevention of further increase in production capacity. However, war that destroys physical installations for the production and/or transport of oil can significantly disrupt oil supplies. In sum, if the outright war scenario is excluded, we expect prices to fall precipitously in the medium term (3-5 years). However, the continued threat of currently-contained civil wars into larger confrontations can maintain the current prices, especially if unprecedented monetary easing continues
The Lateral Distortional Buckling of I-Plate Girders
This paper presents a numerical study for lateral distortional buckling of I-plate girders (LDBIPGs) by using the general-purpose finite element package ABAQUS (version 6.13) software. 3-D finite element (FE) models for simply supported IPGs subjected to two cases of loading are built. The first case of loading was uniform end moment that was introduced by a couple of forces applied at the top and bottom flanges of the IPGs. The second case of loading was a concentrated load at the shear center in the mid-span. First, shell finite element models are validated by comparing the FE critical bending moment (������,����) by the critical bending moment in EC3 code (������,��,������). The results indicate that the ������,���� was in good agreement with ������,��,������. Secondly, a preliminary analysis is conducted to the relative girder slenderness (��) where the LDB too place. Finally, a parametric study is carried out on simply supported IPGs regarding to the span length, the flange cross-section dimensions and the thickness of the web. The results showed that increasing the length of girders decreases ������.���� and increase in the bending coefficient factor (����). Also, decreasing in the web plate slenderness ratio (��������⁄) works on increasing in ������.���� values and ����. The results also showed that the increasing in the thickness of flange increases ������.���� and increase the value of ���� with small value. As a result of parametric study, the mean value and standard deviation of ���� for LDB mode are 1.16 and 0.08 respectively for �� limits (90:130). For �� limits (131:175), the mean value and standard deviation of ���� are 1.27 and 0.03 respectively. As for �� limits (176:221), the mean value and standard deviation of ���� are 1.32 and 0.02 respectively
Stabilization of active acetylene by-product via sequestration of co\u3csub\u3e2\u3c/sub\u3e
© 2020 Taylor & Francis Group, London, UK. The rising rates of carbide lime waste (CLW), the by-product of acetylene production, cause environmental problems and need for the repurposing of the said material. The high content of calcium in such by-products (60–80%) is the main reason for its utilization in CO2 sequestration. This study focused on using of CLW to form simple, reliable, cost-efficient process, applying direct solid-liquid-gas carbonation reaction, which consists of bubbling CO2 gas through an aqueous slurry of slaked CLW with different solid /water ratios. The experimental conditions were adjusted for maximum carbonation efficiency. Experimental results indicated that CLW has the potential to store CO2 in the form of stable carbonates. Considering the total calcium content, an amount of 0.5833 kg CO2 /kg CLW was achieved. The influence of solid/water ratio on the precipitation of calcium carbonate was investigated using SEM that showed a difference in crystal carbonate sizes and morphologies
Proučavanje parametara rasprašivanja plazmom velike gustoće u koaksijalnom ubrzivaču plazme
Plasma accelerator was used for the deposition of a material powder placed at a breach. A capacitor bank of 46.26 µF charged to 3 kV (208.17 J) gave a peak current of 8.8 kA after 15 µs. Plasma inductance varied between 3 µH and 1.5 µH while the plasma resistance varied between 5 mΩ and 300 mΩ within one shot, while the electron temperature and plasma density near the substrate measured with a double electric probe was about 3 eV and 2.7 × 1013 cm−3 , respectively. Carbon plasma velocity at the muzzle was 6.0 cm/µs which agrees with calculations. The deposited graphite powder showed mostly a homogeneous distribution of clusters. The total efficiency of the system, considering both the internal and kinetic energy, was found to be 10.9 %.Rabili smo ubrzivač plazme za naparavanje praha postavljenog na otvoru za snop. Sklop kapacitora od 46.26 µF nabijen na 3 kV (208.2 J) davao je vršnu struju 8.8 kA nakon 15 µs. Indukcija plazme mijenjala se između 3 i 1.5 µH, a otpor plazme između 5 i 300 mΩ tijekom pojedinog palenja. Elektronska temperatura i gustoća plazme u blizini podloge, koje smo mjerili dvostrukom električnom sondom, iznose oko 3 eV odn. 2.7 × 1013 cm−3 . Brzina ugljične plazme kod otvora iznosi 6.0 cm/µs, u skladu s izračunatom vrijednošću. Naparen grafitni prah pokazuje većma jednoličnu raspodjelu nakupina. Ukupna učinkovitost sustava, ubrajajući unutarnju i kinetičku energiju, iznosi 10.9 %
Recurrent Pneumonia in Children Admitted to Assiut University Children Hospital. Magnitude of the Problem and Possible Risk Factors
Background: Incidence data indicate that recurrent pneumonia occurs in 7.7–9% of all children withcommunity acquired pneumonia. We aim by this study to assess the prevalence of recurrent pneumoniaamong the admissions with diagnosis of pneumonia in Assiut university children hospital for one year andto try to define the possible related risk factors. Patients and methods: This is a prospective hospital basedstudy in Assiut University Children’s Hospital. Children younger than 16 years admitted with a hospitaldiagnosis of pneumonia to Assiut University Children’s Hospital for one year from 1 February 2017 to 31January 2018 were included.Results: Approximately 1 in 12 children with pneumonia in our locality have recurrent pneumonia with percentageof 12.61%. Cardiac diseases especially congenital heart diseases was the cause among 25.45%of the cases, immunodeficiency diseases represented 20.9% of the cases ,while bronchial asthma wasthe cause of recurrent pneumonia among 16.36% of the cases. As regard to risk factors in studied group,prematurity was detected among 7.27 % of the cases while more than 50% were formula fed and more than60% exposed to pollution. Father smoking was detected among 36.36% of cases. Patients aged > 6 yearsshowed significantly higher frequency in risk factors as obesity, indoor and outdoor pollution and use ofsteroids in comparison to other age groups. However, patients aged 0-3 years exhibited significantly higher% frequency of having heart disease, oro-motor in coordination /swallowing dysfunction, gastro esophagealreflux and under nutrition as risk factors for recurrent pneumonia in comparison to other age groups.Conclusions: The most frequent underlying cause for recurrent pneumonia in Assiut University Children’sHospital which presents the largest referral pediatric hospital in Upper Egypt for one year according to ourstudy was cardiac diseases; the second most frequent cause was immunodeficiency diseases, followedby bronchial asthma. Risk factors for recurrent pneumonia include socio-economic status of studiedcases, prematurity, exposure to passive smoking and in or outdoor pollution, obesity, under nutrition, lackof breast feeding, gastro esophageal reflux and steroids usage
Proučavanje parametara rasprašivanja plazmom velike gustoće u koaksijalnom ubrzivaču plazme
Plasma accelerator was used for the deposition of a material powder placed at a breach. A capacitor bank of 46.26 µF charged to 3 kV (208.17 J) gave a peak current of 8.8 kA after 15 µs. Plasma inductance varied between 3 µH and 1.5 µH while the plasma resistance varied between 5 mΩ and 300 mΩ within one shot, while the electron temperature and plasma density near the substrate measured with a double electric probe was about 3 eV and 2.7 × 1013 cm−3 , respectively. Carbon plasma velocity at the muzzle was 6.0 cm/µs which agrees with calculations. The deposited graphite powder showed mostly a homogeneous distribution of clusters. The total efficiency of the system, considering both the internal and kinetic energy, was found to be 10.9 %.Rabili smo ubrzivač plazme za naparavanje praha postavljenog na otvoru za snop. Sklop kapacitora od 46.26 µF nabijen na 3 kV (208.2 J) davao je vršnu struju 8.8 kA nakon 15 µs. Indukcija plazme mijenjala se između 3 i 1.5 µH, a otpor plazme između 5 i 300 mΩ tijekom pojedinog palenja. Elektronska temperatura i gustoća plazme u blizini podloge, koje smo mjerili dvostrukom električnom sondom, iznose oko 3 eV odn. 2.7 × 1013 cm−3 . Brzina ugljične plazme kod otvora iznosi 6.0 cm/µs, u skladu s izračunatom vrijednošću. Naparen grafitni prah pokazuje većma jednoličnu raspodjelu nakupina. Ukupna učinkovitost sustava, ubrajajući unutarnju i kinetičku energiju, iznosi 10.9 %
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