scholarly journals DEVICES FOR DETERMINING THE STRENGTH OF SNOW AND ICE FORMATIONS

2021 ◽  
pp. 105-112
Author(s):  
Р.Б. Желукевич ◽  
В.В. Минин ◽  
Ю.Ф. Кайзер ◽  
А.В. Лысянников ◽  
В.Г. Шрам ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Spherical Surface ◽  
Lower Surface ◽  
Strength Properties ◽  
Manufacturing Cost ◽  
Technical Solution ◽  
Technical Result ◽  
Hardness Tester ◽  
Road Pavement ◽  
Under Construction

В статье представлен анализ существующих средств определения прочности снежно-ледовых образований, выявлены их недостатки, преимущества и отличительные способности. Целью данной работы является разработка компактных средств измерения прочности компонентов дорожных покрытий и обеспечения контроля качества уплотнения полотна сооружаемых зимних дорог по глубине покрытия. Предложено техническое решение, которое позволяет достичь более высокого технического результата по сравнению с известными аналогами, который заключается в повышении точности измерений, упрощении фиксации шарового элемента в корпусе, обеспечении фиксации подвижных элементов при транспортировке и расширении функциональных возможностей за счет определения прочности на поверхности и по глубине снежного покрова с наконечниками разного профиля, а также позволяет снизить стоимость изготовления и трудоемкость работ при измерениях. Предложенный прибор (твердомер) позволяет расширить область применения, как для свежевыпавшего снега, так и для лежалого, за счёт применения разных нижних поверхностей профиля наконечников в виде конуса, цилиндра или шара. Шаровая поверхность увеличивает площадь соприкосновения нижней поверхности его со снежными образованиями для свежевыпавшего снега. Прибор спроектирован, изготовлен и позволяет определять прочностные свойства снежно-ледовых образований при выполнении научно-исследовательских работ. The article presents an analysis of the existing means for determining the strength of snow-ice formations, reveals their disadvantages, advantages and distinctive abilities. The purpose of this work is to develop compact means for measuring the strength of road pavement components and ensuring quality control of the compaction of the roadbed of winter roads under construction by the depth of the pavement. A technical solution is proposed that allows achieving a higher technical result in comparison with known analogues, which consists in increasing the measurement accuracy, simplifying the fixing of the ball element in the housing, ensuring the fixation of the moving elements during transportation and expanding the functionality by determining the strength on the surface and in depth snow cover with tips of different profiles, and also allows you to reduce the manufacturing cost and laboriousness of work during measurements. The proposed device (hardness tester) allows you to expand the field of application, both for freshly fallen snow, and for old, due to the use of different lower surfaces of the profile of the tips in the form of a cone, cylinder or ball. The spherical surface increases the contact area of ​​its lower surface with snow formations for freshly fallen snow. The device has been designed, manufactured and allows to determine the strength properties of snow-ice formations during scientific research.

Correlation between the mineral composition and strength properties of sulfate rocks

2021 ◽  
pp. qjegh2020-173
Author(s):  
Mohammad Reza Rahimi ◽  
Seyed Davoud Mohammadi ◽  
Alireza Taleb Beydokhti
Keyword(s):  
Mineral Composition ◽  
Failure Mode ◽  
Strength Properties ◽  
Shear Mode ◽  
Rock Cores ◽  
Strength Tests ◽  
Engineering Problems ◽  
Gypsum Rock ◽  
Under Construction ◽  
First Time

The literature review confirms that the effect of mineral composition on the strength properties of rocks has rarely been studied. One of the most problematic sedimentary rocks is sulfate rocks, which cause engineering problems in the infrastructure sites such as reservoir dams. In this paper, for the first time, the effect of mineral composition on the strength properties of sulfate rocks was investigated. The rock blocks were collected from the Gachsaran Formation outcrops at the four under construction reservoir dam sits in Iran. After preparing, drying and saturation the rock cores samples (329 samples), uniaxial compressive strength tests were performed in accordance with ASTM and ISRM standards. The results of this study confirmed that firstly, there is a correlation between the mineral composition and the strength properties of the sulfate rocks, but the obtained relationships do not have the necessary certainty to be used as predictive equations. Secondly, by increasing the amount of anhydrite or microcrystalline carbonates in a gypsum rock, its strength properties are increased. Thirdly, in a dry condition the dominant failure mode in gypsum and anhydrite rocks is a shear and dilatation mode, respectively, but after saturation, the failure mode tends to shear mode.

scholarly journals Arrangement of construction joints in cast-in-place slabs

2019 ◽  
Vol 97 ◽  
pp. 04023
Author(s):  
Irina Yakovleva ◽  
Valentina Kurochkina
Keyword(s):  
Reinforced Concrete ◽  
Strength Properties ◽  
Concrete Slabs ◽  
Construction Joint ◽  
Regulatory Documents ◽  
Reinforced Concrete Slabs ◽  
Early Removal ◽  
Construction Joints ◽  
Under Construction

Within latest decades cast-in-place construction of residential houses has been actively developed. Works on erection of cast-in-place frame of the building are normally performed by phases, which results in a necessity to arrange construction joints of concreting. In accordance with regulatory documents, it is allowed to arrange construction joints in any place of the slab, in parallel with its less side. As well, it is necessary to observe the technology for joint arrangement. As practice shows, observing only technology of construction joint arrangement is insufficient to provide for strength properties of cast-in-place reinforced-concrete slabs. This article provides an analysis of actual geodetic pre-construction surveys, design and theoretically-calculated solutions; case study is a multistoried building under construction. On which basis, excessive slab deflections in the places of construction joints, were detected. It is established, that the main reason for deflection occurrence is early removal of slab formwork and installation of supports for temporary supporting. On the basis of obtained findings authors make conclusions regarding compulsory observance of the technology for construction joint arrangement, regarding a necessity to remove formwork according to common standards 70.13330.2012; as well, it is recommended to leave formwork under construction joints until concrete gains 100% of ruggedness.

THREE FACE ATTACHMENT RETROFIT AGAINST FATIGUE CRACKING AT STEEL GIRDER WEB PENETRATION

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Chihiro Sakamoto ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Stress Reduction ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Lower Surface ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Lower Side ◽  
Steel Girder

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties. In this study, we investigate stress reduction effects of three face attachment retrofit through fatigue tests using a large girder specimen with web penetration details where cross beam lower flanges are connected to the lower surface of a slot by welding. As a result, there is very little difference between two and three face attachments about stress reduction effects, while they are more effective than one face attachment. The upper side attachment is more effective than the lower side attachment, while both side attachment is best. Two and three face both side attachments can reduce about 40% of stress concentration, while two and three face upper side attachments can reduce 50– 60%.

A NEW WAY OF TUBULAR LINE LAYING AT THE HEIGHT OF BUILDING PARALLEL STAIR

2014 ◽  
Vol 4 (3) ◽  
pp. 52-59
Author(s):  
Nikolay Alekseevich ILYIN ◽  
Dmitry Sergeevich KOMAROV ◽  
Denis Vladimirovich LITVINOV
Keyword(s):  
Technical Solution ◽  
Technical Result

A new technical solution according to the method of fire sleeve line laying in parallel stairs to bring water for fire suppressing is proposed. The use of the invention provides a positive technical result.

RETROFITTING METHODS AGAINST FATIGUE CRACKING IN STEEL GIRDER WEB PENETRATION

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Chihiro Sakamoto ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Lower Surface ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Stress Distributions ◽  
Steel Girder ◽  
Cracking Behavior ◽  
Weld Toe

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In a previous report, we investigated the stress distributions around web penetration details, and fatigue cracking behavior, using steel girder specimens with web penetration details. In this study, we investigate effects of retrofitting methods against fatigue cracking in web penetration details through fatigue tests using large girder specimens with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. Principal results obtained through this study are as follows: (1) Weld toe grinding can extend fatigue life more than 5 times, (2) Two-face attachment can extend fatigue life more than 10 times, and (3) Two-face attachment with weld toe grinding can extend fatigue life more than 25 times.

scholarly journals Modeling Small Scale Solar Powered ORC Unit for Standalone Application

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Enrico Bocci ◽  
Mauro Villarini ◽  
Luca Bove ◽  
Stefano Esposto ◽  
Valerio Gasperini
Keyword(s):  
Power Generation ◽  
Ad Hoc ◽  
Rankine Cycle ◽  
External Support ◽  
Working Fluid ◽  
Small Scale ◽  
Technical Solution ◽  
Solar Panels ◽  
Under Construction ◽  
Photovoltaic Generators

When the electricity from the grid is not available, the generation of electricity in remote areas is an essential challenge to satisfy important needs. In many developing countries the power generation from Diesel engines is the applied technical solution. However the cost and supply of fuel make a strong dependency of the communities on the external support. Alternatives to fuel combustion can be found in photovoltaic generators, and, with suitable conditions, small wind turbines or microhydroplants. The aim of the paper is to simulate the power generation of a generating unit using the Rankine Cycle and using refrigerant R245fa as a working fluid. The generation unit has thermal solar panels as heat source and photovoltaic modules for the needs of the auxiliary items (pumps, electronics, etc.). The paper illustrates the modeling of the system using TRNSYS platform, highlighting standard and “ad hoc” developed components as well as the global system efficiency. In the future the results of the simulation will be compared with the data collected from the 3 kW prototype under construction in the Tuscia University in Italy.

scholarly journals Effect of Sampietrini Pavers on Urban Heat Islands

2021 ◽  
Vol 18 (24) ◽  
pp. 13108
Author(s):  
Laura Moretti ◽  
Giuseppe Cantisani ◽  
Marco Carpiceci ◽  
Antonio D’Andrea ◽  
Giulia Del Serrone ◽  
...  
Keyword(s):  
Air Temperature ◽  
Urban Areas ◽  
Lower Surface ◽  
Early Morning ◽  
Urban Heat Islands ◽  
Predicted Mean Vote ◽  
Heat Islands ◽  
The Road ◽  
Road Pavement ◽  
Microclimatic Conditions

Cool pavements are reflective and/or permeable pavements that improve microclimate of urban areas where heat islands cause discomfort to citizens. Stone pavements lower surface temperatures and reduce the amount of heat absorbed. This study assessed, using ENVI-met 4.3 LITE software, how air temperature and predicted mean vote depend on physical properties of the road pavement. A comparative microclimatic analysis was implemented on a rectangular square in Rome (Italy) in the summer, paved in three different ways: asphalt, traditional sampietrini, and permeable sampietrini. The model considered local weather parameters, surrounding fabric, and vegetation to give reliable results in terms of numerical and graphical output using the application tool Leonardo. The tested pavement types affected air temperature during the day, but did not influence this variable in the early morning. Permeable sampietrini pavement was more effective than traditional sampietrini pavement in reducing air temperature compared to the current asphalt surface. The road pavement did not, however, affect human comfort in terms of predicted mean vote. The obtained results are useful for further investigation of parameters that could modify the microclimatic conditions of urban areas.

scholarly journals Capabilities for Probing of Upper Atmosphere Density Variations and Seismic-Orbital Effects Using Small-Size Spacecraft

2020 ◽  
Vol 11 (4) ◽  
pp. 305-312
Author(s):  
A. V. Tertyshnikov
Keyword(s):  
Cost Effectiveness ◽  
Seismic Hazard ◽  
Upper Atmosphere ◽  
Technical Solution ◽  
Technical Result ◽  
Ballistic Coefficient ◽  
Falling Spheres ◽  
Atmosphere Density

The miniature spacecraft have a high ballistic coefficient, which is advantageous for the resolution of sensing the density  of  the  upper  atmosphere.  The  purpose  of  this  work  is  to  show  new  features of the "falling spheres method" based on the miniaturization of the Spacecraft. The "falling spheres method" is used to probe variations in the density of the upper atmosphere.A technical solution for diagnostics of orbital sections with abnormal changes in the speed and acceleration of  spacecraft  equipped  with  onboard  navigation  receivers  and  micro-accelerometers is considered.The technical result of the proposed development is the efficiency and cost – effectiveness of sounding variations in the density of the upper atmosphere, seismic-orbital effects-variations in the density of the atmosphere over earthquake-regions and the seismic hazard.

scholarly journals EFFECT OF NITROGEN HYDROGEN RATIO ON PLASMA NITRIDING FOR 38CrMoAl

2018 ◽  
Vol 24 (3) ◽  
pp. 229
Author(s):  
Lu Song ◽  
Tiantian Peng ◽  
Xiaobin Zhao ◽  
Jing Hu
Keyword(s):  
Plasma Nitriding ◽  
High Surface ◽  
Surface Hardness ◽  
Lower Surface ◽  
Compound Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardness Tester ◽  
Modified Surface ◽  
Modified Surface Layer

<p class="AMSmaintext">Critical nitrogen hydrogen ratio in plasma nitriding was primarily investigated to get enhanced performance for 38CrMoAl steel. The modified surface layer was characterized by optical microscopy (OM), X-ray diffraction (XRD) and micro-hardness tester. The results showed that the critical nitrogen hydrogen ratio was 1: 5 while plasma nitriding at 540℃ for 6 h. Under this condition, no compound layer was formed, and accompanied with high surface hardness, while the compound layer was formed accompanied with lower surface hardness with nitrogen hydrogen ratio higher than the critical value.</p>

Kovalev passive rangefinder

2021 ◽  
Vol 969 (3) ◽  
pp. 12-18
Author(s):  
S.V. Kovalev ◽  
D.A. Shapovalov
Keyword(s):  
Measurement Accuracy ◽  
Distance Measurement ◽  
Optical Path ◽  
Optical Scheme ◽  
Acceptable Error ◽  
Technical Result ◽  
Laser Range Finders ◽  
Digital Methods ◽  
Field Works ◽  
Photo Receiver

The authors present the results of longtime research on the development and improvement of a passive geodetic rangefinder based on the inbasis method of distance measurement. Actually, active laser range finders are not always effective at field works. An original compact optical scheme of a passive rangefinder based on a theodolite telescope and a mould photo receiver with application of digital methods for coordinate calculation is proposed. The distance and dimensions of the object are defined. The former is identified by the shift between the images on the horizontal axis. The merit of such a system is the absence of mechanical displacements. Its main advantage is an extremely simple optical path. The technical result is reduction in overall dimensions and weight, while maintaining an acceptable error in the passive range measurement. The use of Kovalev passive rangefinder is promising at performing geodetic measurements with total stations. There is also a description of the rangefinder sample as well as the calculations results according to the distance measurement accuracy.

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