Results 81 to 90 of about 4,362 (259)

Perceived importance and didactic difficulty of chemistry education: Insights from Czech teachers

The Curriculum Journal, EarlyView.
Abstract This empirical study examines how chemistry teachers in lower and upper secondary schools in the Czech Republic evaluate the content of the chemistry curriculum, focussing on its perceived importance and didactic difficulty. Based on a quantitative survey (N = 146), the study provides insight into the pedagogical content knowledge of ...
Jitka Lorenzová, Blanka Jirkovská, Martin Čapek Adamec, Jan Havlík, Petr Holzhauser, Daniela Nováková, Karel Němejc   +6 more
wiley   +1 more source

Review and prospects of shear test of bolted rock joints

Deep Underground Science and Engineering, EarlyView.
The laboratory shear test equipment, test method, and numerical simulation of bolted rock joints were summarized. The shortcomings and limitations of the current research were analyzed, and the research prospects were proposed. Abstract Rock bolting is a critical approach in geotechnical engineering for supporting weak rocks.
Shulin Ren, Fan Yang, Manchao He, Yong Yuan, Zhigang Tao   +4 more
wiley   +1 more source

Porcelain Polishing Residue as a Supplementary Cementitious Material in Self-Compacting Concrete: Pozzolanic Activity and Performance Assessment

Powders
The increasing demand for sustainable construction materials has intensified research on supplementary cementitious materials capable of reducing Portland cement consumption and associated CO2 emissions. In this context, porcelain polishing residue (PPR),
Alexandre Serafim, Elaine Antunes, Gláucia Dalfré, Ricardo de Almeida   +3 more
doaj   +1 more source

Freeze-Thaw Resistance of Cement Screed with Various Supplementary Cementitious Materials

Reviews on Advanced Materials Science, 2019
This paper describes a study of the effect of partial replacement of ordinary Portland cement (OPC) by various mineral additives in the screed mixtures. Ceramic powder, blast furnace slag and fly ash were gradually employed in increments of 12.5 wt.% up ...
Reiterman Pavel, Holčapek Ondřej, Zobal Ondřej, Keppert Martin   +3 more
doaj   +1 more source

Multiple injection techniques to stimulate complex fracture networks in coal reservoirs: A case study on gas disaster reduction of subsurface coal mine in southwest China

Deep Underground Science and Engineering, EarlyView.
An experimental device for physical simulation of hydraulic fracturing, comprising: a load‐bearing mechanism with multiple interconnected plates that collectively form an sample chamber; a load‐generating mechanisms, with multiple load‐generating mechanisms arranged within the experimental chamber.
Delei Shang, Farui Shi, Jun Lu, Minghui Li, Cunbao Li, Heping Xie   +5 more
wiley   +1 more source

Advancing mine pillar design: Evaluating traditional methods and integrating AI for enhanced stability of pillars in the Great Dyke, Zimbabwe

Deep Underground Science and Engineering, EarlyView.
B1 is bord width 1, B2 is bord width 2, L is the pillar length, W is the pillar width, red color and letter A represent the pillars, and white color and number 1 represent excavated areas. Pstress is the average pillar stress; σv is the vertical component of the virgin stress, MPa; and e is the areal extraction ratio. e = B o B o + B P ${\rm{e}}=\frac{{
Tawanda Zvarivadza, Hendrik Grobler, Peter Apata Olubambi, Moshood Onifade, Manoj Khandelwal   +4 more
wiley   +1 more source

Fracture evolution of a thick soft protection layer and the water inrush mechanism in overburden under longwall mining

Deep Underground Science and Engineering, EarlyView.
Through shear–tensile creep tests and viscoelastic modeling, the fracture evolution of thick soft protective layers is clarified. Results show thickness‐dependent rheological failure modes that govern four types of roof water inrush, providing a mechanism‐based framework for hazard prediction and control. Abstract In the Jurassic coal‐bearing strata of
Mengnan Liu, Wei Qiao, Xianggang Cheng, Xiangsheng Meng, Peichao Feng   +4 more
wiley   +1 more source

Mechanism and disaster control new technology of strong ground pressure manifestation in ultra‐large mining face

Deep Underground Science and Engineering, EarlyView.
In response to the problem of strong mining pressure manifestation along the goaf roadway in a thick coal seam mining area, this study uses a new type of combined blasting roof cutting technology to effectively control the manifestation and deformation of mining pressure along the goaf roadway.
Xiaoding Xu, Manchao He, Jun Yang, Yubing Gao, Qiang Fu, Qing Ma, Yajun Wang   +6 more
wiley   +1 more source

Enhancing performance of recycled aggregate concrete with supplementary cementitious materials

Cleaner Materials
The substitution of natural coarse aggregates (NCA) by recycled coarse aggregates (RCA) is part of the environmental approach aimed at reducing waste and preserve natural resources.
Abba Fatiha, Ezziane Karim, Adjoudj Mhamed, Farid Abed   +3 more
doaj   +1 more source

Dynamic response at the terminus of oblique intersecting joints subjected to stress waves

Deep Underground Science and Engineering, EarlyView.
This study derives the propagation equation for stress waves impinging upon nonlinear oblique intersecting joints. It analyzes the dynamic response at the terminus of nonlinear oblique intersecting joints subjected to stress waves. Abstract To investigate the dynamic response at the terminus of oblique intersecting joints subjected to stress waves, a ...
Gang Hu, Xiang Chen, Honglu Fei, Shijie Bao, Jian Guo   +4 more
wiley   +1 more source