Recycling red mud from the production of aluminium as a red cement-based mortar

2017 ◽  
Vol 35 (5) ◽  
pp. 500-507 ◽  
Author(s):  
Xiaojie Yang ◽  
Jianfeng Zhao ◽  
Haoxin Li ◽  
Piqi Zhao ◽  
Qin Chen
Keyword(s):  
Red Mud ◽  
Mechanical Performance ◽  
Effective Management ◽  
Current Management ◽  
New Approach ◽  
Air Content ◽  
Negative Effect ◽  
Series Of Experiments ◽  
Hardened Properties ◽  
Performance Variations

Current management for red mud is insufficient and a new method is needed. A series of experiments have been carried out to develop a new approach for effective management of red mud. Mortars without or with 3%, 6% and 9% red mud were prepared and their fresh and hardened properties were measured to access the possibility of recycling the red mud in the production of red cement-based mortar. The mechanisms corresponding to their mechanical performance variations were explored by X-ray powder diffraction and scanning electron microscopy. The results show that the fresh mortars with red mud present an increase of viscosity as compared with the control. However, little difference is found when the content of red mud is altered. It also can be seen that red mud increases flow time and reduces the slump flow of the mortar. Meanwhile, it is found that mortar with red mud is provided with higher air content. Red mud is eligible to adjust the decorative mortar colour. Compressive strength of mortar is improved when less than 6% red mud is added. However, overall it has a slightly negative effect on tensile bond strength. It decreases the Ca(OH)2 content and densifies the microstructure of hardened paste. The heavy metal concentrations in leachates of mortars with red mud are much lower than the values required in the standard, and it will not do harm to people’s health and the environment. These results are important to recycle and effectively manage red mud via the production of red cement-based mortar.

Managing bird populations: for whom and at what cost?

1997 ◽  
Vol 3 (3) ◽  
pp. 172 ◽  
Author(s):  
John L. Craig
Keyword(s):  
Sustainable Development ◽  
Human Activities ◽  
Financial Incentives ◽  
The Other ◽  
Effective Management ◽  
Single Factor ◽  
Natural Ecosystems ◽  
Bird Populations ◽  
Economic Attitudes ◽  
Negative Effect

Conservation is a necessary component of sustainable development. Human activities have had and continue to have a negative effect on natural ecosystems. There is a need to move to a more co-operative, effective and accountable management of "communal resources" including fauna and flora. Many issues negatively influence the ability of conservation managers to perform well and for all stakeholders. Society's underlying philosophic and economic attitudes are important. Most contemporary Southern Hemisphere societies see nature as separate from people and manage with a welfare mentality. Most financial incentives favour degraders of natural values and penalize those who conserve or behave sustainably. The other major issue which precludes effective management is the approach of government managers. Performance tends to be patchy, unaccountable and often based on simplistic single factor notions. There appears to be a general failure to provide diversified products to different stakeholders. These issues with suggestions for improvement are discussed with special reference to the management of rare bird populations and of fire.

scholarly journals Backbone cup – a structure design competition based on topology optimization and 3D printing

2016 ◽  
Vol 7 ◽  
pp. A1 ◽  
Author(s):  
Ji-Hong Zhu ◽  
Kai-Ke Yang ◽  
Wei-Hong Zhang
Keyword(s):  
Topology Optimization ◽  
3D Printing ◽  
Experimental Approach ◽  
Mechanical Performance ◽  
Turnaround Time ◽  
Structure Design ◽  
The Finite Element Method ◽  
New Approach ◽  
Design Competition ◽  
Testing Approach

This paper addresses a structure design competition based on topology optimization and 3D Printing, and proposes an experimental approach to efficiently and quickly measure the mechanical performance of the structures designed using topology optimization. Since the topology optimized structure designs are prone to be geometrically complex, it is extremely inconvenient to fabricate these designs with traditional machining. In this study, we not only fabricated the topology optimized structure designs using one kind of 3D Printing technology known as stereolithography (SLA), but also tested the mechanical performance of the produced prototype parts. The finite element method is used to analyze the structure responses, and the consistent results of the numerical simulations and structure experiments prove the validity of this new structure testing approach. This new approach will not only provide a rapid access to topology optimized structure designs verifying, but also cut the turnaround time of structure design significantly.

Determination of optimum tuber planting density for production of tubers in processing ware grades in the potato variety Record

1990 ◽  
Vol 114 (1) ◽  
pp. 11-18 ◽  
Author(s):  
D. C. E. Wurr ◽  
J. R. Fellows ◽  
R. A. Sutherland ◽  
E. J. Allen
Keyword(s):  
Seed Tuber ◽  
Planting Density ◽  
Potato Tubers ◽  
New Approach ◽  
Seed Tubers ◽  
Series Of Experiments ◽  
Number Of Stems ◽  
The Uk ◽  
Seed Tuber Weight

SUMMARYA series of experiments examining the influences of size and spacing of planted potato tubers (‘seed’ tubers) on tuber yields was conducted at four sites in the UK in 1982–84. A new approach to data analysis was used to estimate the optimum tuber planting density for different ware grades. The optimum density, which maximized returns, decreased with increasing seed tuber weight and ratio of seed-tuber cost to ware value and with lower than average total tuber yields. Changing the required ware grade from 40–65 mm to 40–80 mm had a minimal effect on the optimum tuber planting density.Optimum tuber planting densities were lower than in published recommendations but this disparity appeared to be accounted for by differences in the number of stems produced by each planted tuber. There was some evidence that, with lower seed-tuber weights, the optimum planting density differed with site and that at optimum economic densities small and medium seed tubers outyielded large seed tubers.

scholarly journals Effects of Prohexadione-Ca and GA4+7 on Scarf Skin and Fruit Maturity in Apple

HortScience ◽  
2006 ◽  
Vol 41 (7) ◽  
pp. 1602-1605 ◽  
Author(s):  
Steven McArtney ◽  
Dave Ferree ◽  
John Schmid ◽  
J.D. Obermiller ◽  
A. Green
Keyword(s):  
Fruit Quality ◽  
Economic Benefits ◽  
Quality Parameters ◽  
Fruit Weight ◽  
Single Application ◽  
Early Season ◽  
Fruit Maturity ◽  
Negative Effect ◽  
Series Of Experiments

A series of experiments were undertaken to compare the effects of individual and combined applications of GA4+7 and prohexadione-Ca (P-Ca) on scarf skin and fruit quality parameters on red strains of `Rome Beauty' and `Gala' apples. Three applications of GA4+7 at 10-day intervals beginning at petal fall (PF) significantly reduced scarf skin severity in all experiments. A single application of P-Ca at PF had no effect on scarf skin in one experiment but reduced scarf skin severity in two further experiments. Combining P-Ca with the first of three GA4+7 sprays as a tank mix reduced the severity of scarf skin more effectively than either material alone in two of three experiments at P < 0.05 and in all three experiments at P < 0.10. Combining P-Ca with the first application of GA4+7 as a tank mix generally reduced scarf skin as effectively as applying P-Ca and the first GA4+7 spray two days apart, although in one experiment, greater scarf skin control was achieved when P-Ca was applied 2 days after the first GA4+7 spray. A single application of P-Ca at PF consistently reduced, and three applications of GA4+7 consistently increased, mean fruit weight at harvest compared with the control. The economic benefits as a result of reducing scarf skin severity with P-Ca and GA4+7 sprays will need to be balanced against the negative effect of P-Ca on mean fruit weight. There is no antagonism between early season P-Ca and GA4+7 sprays for scarf skin control, and P-Ca may increase the efficacy of GA4+7 sprays for scarf skin control in apple.

scholarly journals A New Approach for Designing Fluid Concrete with Low Cement Content: Optimization of Packing Density of Aggregates

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4082
Author(s):  
Ning Zhang ◽  
Wenqiang Zuo ◽  
Wen Xu ◽  
Shenyou Song
Keyword(s):  
Compression Strength ◽  
Packing Density ◽  
Cement Content ◽  
Drying Shrinkage ◽  
Simple Method ◽  
New Approach ◽  
Concrete Mixtures ◽  
Slump Flow ◽  
Cementitious Binder ◽  
Hardened Properties

The current study aims at proposing a novel and simple method for designing fluid concrete such as self-compacting concrete (SCC) with a low cementitious binder content to reduce the carbon footprint. Different testing methods regarding the packing density of aggregate mixtures are performed and compared. The W/C was determined according to the target compression strength. Slump flow spread is carried out to determine the most appropriate superplasticizer (SP) dosage and aggregate volume fractions and proportions in concrete mixtures. Furthermore, hardened performance, including compression strength and drying shrinkage of the fluid concrete, are characterized. Finally, a mix design process of fluid concrete with low cement content was proposed based on the preferred fresh and hardened properties of the concrete mixtures.

scholarly journals Influence of red mud addition on rheological behavior and hardened properties of mortars

2014 ◽  
Vol 65 ◽  
pp. 84-91 ◽  
Author(s):  
L. Senff ◽  
R.C.E. Modolo ◽  
A. Santos Silva ◽  
V.M. Ferreira ◽  
D. Hotza ◽  
...  
Keyword(s):  
Rheological Behavior ◽  
Red Mud ◽  
Hardened Properties

Social Queues (Cues): Impact of Others’ Waiting in Line on One’s Service Time

2022 ◽  
Author(s):  
Sezer Ülkü ◽  
Chris Hydock ◽  
Shiliang Cui
Keyword(s):  
Service Time ◽  
Operations Management ◽  
Social Influences ◽  
Social Systems ◽  
Concern For Others ◽  
Negative Effect ◽  
Series Of Experiments

The traditional queueing literature assumes that service time is largely independent of social influences. However, queues are social systems; and social considerations are therefore likely to impact customers’ service time decision to the extent they have control. Through a series of experiments, we show that when others are waiting in line, customers tend to accelerate their own service time, and in doing so, sacrifice their own consumption utility. This behavior is driven by concern for others. Notably, the effect is diminished when they themselves have waited, as it is perceived as fair to let others wait if one also had to wait. We further show that obscuring the visibility between customers in service and those waiting in line diminishes the negative effect of others queueing on one’s own service time. This paper was accepted by Jay Swaminathan, operations management.

Mechanical Properties of Additively Manufactured Periodic Cellular Structures and Design Variations

2021 ◽  
pp. 1-48
Author(s):  
Derek G. Spear ◽  
Anthony N. Palazotto ◽  
Ryan A. Kemnitz
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Material Selection ◽  
Cellular Structures ◽  
New Approach ◽  
Triply Periodic ◽  
Superior Mechanical Properties ◽  
Manufacturing Technologies ◽  
Surface Thickness

Abstract Advances in manufacturing technologies have led to the development of a new approach to material selection, in that architectured designs can be created to achieve a specific mechanical objective. Cellular lattice structures have been at the forefront of this movement due to the ability to tailor their mechanical response through tuning of the topology, surface thickness, cell size, and cell density. In this work, the mechanical properties of additively manufactured periodic cellular lattices are evaluated and compared, primarily through the topology and surface thickness parameters. The evaluated lattices were based upon triply periodic minimal surfaces (TPMS), including novel variations on the base TPMS designs, which have not been tested previously. These lattices were fabricated out of Inconel 718 (IN718) through the selective laser melting (SLM) process. Specimens were tested under uniaxial compression, and the resultant mechanical properties were determined. Further discussion of the fabrication quality and deformation behavior of the lattices are provided. Results of this work indicate that the Diamond TPMS lattice has superior mechanical properties to the other lattices tested. Additionally, with the exception of the Primitive TPMS lattice, the base TPMS designs exhibited superior mechanical performance to their derivative lattice designs.

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