Study on Construction Blasting Vibration Control and Effect of Space Coupling of the Large Cavern under High Crustal Stress

2011 ◽  
Vol 368-373 ◽  
pp. 2908-2914
Author(s):  
Sheng Xiang Lei ◽  
Bo Gao
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Field Trials ◽  
Blasting Vibration ◽  
Underground Structures ◽  
Crustal Stress ◽  
Construction Methods ◽  
Geological Conditions ◽  
Vibration Attenuation ◽  
The Impact

Taken extremely complex and specific underground chamber excavation of TBM assembly in Jinping Ⅱ Hydropower Station as the background, the research was done on construction blasting vibration effects and control technology in the large cavern under high crustal stress. Combined theoretical analysis with field trials and other methods, chamber controlled blasting program and its parameters of better control of blasting vibrations were set in regard with the geological conditions of TBM assembly chamber, cross-section shape and size, chamber body structure and sequence of construction methods. The blasting vibration test program under complex conditions and measuring points were arranged appropriately. The result is that the blasting vibration attenuation coefficient values and was 1.24 and 0.56. Practice shows that the impact of blasting vibration on rock and underground structures is lesser, therefore the chamber driving speed and construction safety can be ensured by the chamber controlled blasting technology for construction. The blasting vibration attenuation that is deduced from the practice can better reflect the effect of blasting vibration chamber: according to the correlation between dose and level distance of blasting, safe construction blasting can be guided. In addition, there is a greater relevance between blasting vibration control method, materials and strength of underground structures. As blasting dose is the same, with increased age and strength of concrete, its ability to withstand the intensity of blasting vibration is also increased dramatically.

Vibration Propagation Law in Different Areas of Tunnel Face Caused by Blasting

2015 ◽  
Vol 744-746 ◽  
pp. 1005-1009
Author(s):  
Jian Jun Shi ◽  
Li Xue ◽  
Qi Zhang ◽  
Hai Li Meng
Keyword(s):  
Attenuation Coefficient ◽  
Blasting Vibration ◽  
Tunnel Face ◽  
Attenuation Law ◽  
Geological Conditions ◽  
Propagation Law ◽  
Blasting Excavation ◽  
Attenuation Index ◽  
Vibration Attenuation ◽  
Cutting Zone

According to the position and role of borehole, the tunnel face is divided into three regions undercutting area, auxiliary area and surrounding areas and each region have different blasting vibration attenuation law. Using blasting vibration testing instrument TC-4850, the vibration caused by blasting excavation in different region of Chongqing terminal connecting line tunnel was monitored and analyzed, and the vibration characteristics and attenuation law of different region in tunnel face were gained. The results show that: the maximum blasting vibration value was produced in cutting area of tunnel; using the partial excavation and setting large diameter hollow hole in the cut area can effectively reduce the blasting vibration, and the more the number of hollow hole, the damping effect was more significant; vibration attenuation parameters were different in different blasting area in tunnel face and with the increase of excavation area, the vibration attenuation coefficient was gradually decreased. Vibration attenuation index was determined by the geological conditions, basically unchanged, the value of the auxiliary area was 0.5~0.67 times the cutting zone, the value of the surrounding area was 0.25~0.33 times the cutting zone. When adopting sub-steps and sub-regional excavation in small spacing tunnel of Chongqing area, vibration attenuation coefficient can be valued by cutting areas 110~120, auxiliary area 60~80, surrounding region 30~40 and vibration attenuation index can be valued by cutting area 1.5, auxiliary and surrounding region 1.6.

scholarly journals MECHANIZED MANAGEMENT OF PRUNING RESIDUES IN SWEET CHESTNUT ORCHARDS

AGROFOR ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Roberto TOMASONE ◽  
Carla CEDROLA ◽  
Mauro PAGANO ◽  
Andrea ACAMPORA ◽  
Enrico SANTANGELO
Keyword(s):  
Control Method ◽  
Insect Pest ◽  
Parasitoid Wasp ◽  
Work Capacity ◽  
Field Trials ◽  
Single Step ◽  
Sweet Chestnut ◽  
Pruning Residues ◽  
Calorific Power ◽  
The Impact

In Italy, Dryocosmus kuriphilus is a major insect pest of chestnut orchards causinggall formation and significant yield losses. The use of the parasitoid wasp Torymussinensis is an effective biological control method that requires the appropriatemanagement of the pruning residues, to preserve the woody galls in which T.sinensis adults overwinter. An innovative tractor-pulled combined mechanicalshredder was tested for treating the residues, once the pruning operations arecompleted. The machine processes the residues in a single-step, picking-up theprunings from the orchard floor, shredding them to appropriate size, and collectingthem into a rear container. The shredded residues may then be concentrated into afew piles for the long-term field storage, until next spring. The aim of the studywas to evaluate the machinery’s operative performance, the quality of the shreddedbiomass and the impact on gall integrity. In the field trials, the machineryeffectively shredded the residues achieving an average operative capacity of 1.19ha∙h-1 and a work capacity of 1.79 t∙h-1. Moisture content, apparent bulk density,and particle size distribution of the shredded biomass were determined. Over 95%of wood chips were included in the 3.15-45 mm size range, making them suitablefor use in residential biomass furnaces. The calorific power of the chestnut residueswas similar to that reported for other hardwood species (18-20 MJ∙kg-1). Also, themechanical action of the shredder preserved at least two thirds of the winter galls,safeguarding the parasitoid’s life cycle.

Finite Frequency Robust Vibration Control of Flexible-Rigid Coupled Spacecraft

2020 ◽  
Author(s):  
Shidong Xu
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Vibration Modes ◽  
Frequency Range ◽  
Finite Frequency ◽  
Frequency Constraint ◽  
Vibration Attenuation ◽  
Specific Frequency ◽  
Vibration Attenuation Performance ◽  
Frequency Controller

Abstract This paper is concerned with robust vibration control of flexible-rigid coupling spacecraft with finite frequency constraint. Considering that the major vibration energy of flexible structure is induced by the vibration modes located in a specific frequency range, the dynamics of the considered spacecraft are derived as a system with given vibration modes. A novel robust finite frequency controller is proposed by using output feedback method, which focuses on suppressing the vibration modes in given frequency region. Compared with the classic entire frequency controller, the newly proposed controller can achieve better vibration attenuation performance. Finally, illustrative simulation results are provided to demonstrate the effectiveness and superiority of our proposed control method.

THE IMPACT OF MINERAL FERTILIZERS ON THE BIOLOGICAL YIELD OF SUGAR BEET CROP (BETA VULGARIS L. VAR. SACCHARIFERA)

2018 ◽  
Vol 28 (4) ◽  
pp. 1281-1284
Author(s):  
Petar Petrov ◽  
Bojan Mitrovski
Keyword(s):  
Sugar Beet ◽  
Field Trials ◽  
Mineral Fertilizers ◽  
Qualitative Properties ◽  
New Production ◽  
Economic Significance ◽  
Random Block ◽  
Biological Yield ◽  
Sugar Beet Crop ◽  
The Impact

Due to the great economic significance of the sugar beet, the new production trends are aimed at improving the quantitative and qualitative properties and one of the basic agro technical measures that is directly dependent on the yield and quality of the turnip is the properly conducted plant nutrition. Exporting high quantities of nutrients from the soil, the sugar beet requires application of advanced agro-technology, primarily application of adequate and controlled nutrition and irrigation. Application of this measure, in combination with soil processing, has sustained influence over the following cultures in the crop rotation in terms of nutrients regiment and fight against weeds.In order to determine the effects of mineral fertilizers on sugar beet, field experiment was conducted on fluvisol soil. The experiment is set according to a random block system, following the standard methods of agricultural chemistry for conducting field trials. The experiment includes eight variants, as follows: 1. Control (non-fertilized), 2. NP, 3. NK, 4. PK, 5. NPK, 6. N2PK, 7. N2P2K, 8. N3PK.In the phase of technological maturity of sugar beet, collection of the vegetative material and measurement of the height of the biological yield of the turnips was carried out. Based on the survey results, it can be concluded that the variant N2P2K has achieved the highest yield of swollen roots, i.e. 69.330 kg/ha. The highest yield of leafy greens was achieved in the variant N3PK, i.e. 41.920 kg/ha, which indicates the fact that nitrogen has direct influence over the vegetation mass of sugar beet.

scholarly journals A Variable Parameter Ambient Vibration Control Method Based on Quasi-Zero Stiffness in Robotic Drilling Systems

Machines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 67
Author(s):  
Laixi Zhang ◽  
Chenming Zhao ◽  
Feng Qian ◽  
Jaspreet Singh Dhupia ◽  
Mingliang Wu
Keyword(s):  
Vibration Control ◽  
Vibration Isolation ◽  
Control Method ◽  
Control Strategies ◽  
Equations Of Motion ◽  
Variable Parameter ◽  
Harmonic Balance Method ◽  
Variable Stiffness ◽  
Ambient Vibration ◽  
Robotic Drilling

Vibrations in the aircraft assembly building will affect the precision of the robotic drilling system. A variable stiffness and damping semiactive vibration control mechanism with quasi-zero stiffness characteristics is developed. The quasi-zero stiffness of the mechanism is realized by the parallel connection of four vertically arranged bearing springs and two symmetrical horizontally arranged negative stiffness elements. Firstly, the quasi-zero stiffness parameters of the mechanism at the static equilibrium position are obtained through analysis. Secondly, the harmonic balance method is used to deal with the differential equations of motion. The effects of every parameter on the displacement transmissibility are analyzed, and the variable parameter control strategies are proposed. Finally, the system responses of the passive and semiactive vibration isolation mechanisms to the segmental variable frequency excitations are compared through virtual prototype experiments. The results show that the frequency range of vibration isolation is widened, and the stability of the vibration control system is effectively improved without resonance through the semiactive vibration control method. It is of innovative significance for ambient vibration control in robotic drilling systems.

Applying Synthetic Control Method to Estimate the Impact of the Lava Jato Operation on the Worldwide Governance Indicators in Brazil

2021 ◽  
pp. 2631309X2110178
Author(s):  
Eduardo Carvalho Nepomuceno Alencar ◽  
Bryant Jackson-Green
Keyword(s):  
Rule Of Law ◽  
Control Method ◽  
Synthetic Control ◽  
Synthetic Control Method ◽  
The Rule Of Law ◽  
Governance Indicators ◽  
Regulatory Quality ◽  
Legal Judgments ◽  
The Impact ◽  
Control Of Corruption

In 2014, the most prominent anti-corruption investigation in Latin America called Lava Jato, exposed a Brazilian corruption scheme with reverberations in 61 countries, resulting in legal judgments for nearly 5 billion USD in reimbursements thus far. This article applies the synthetic control method on data from 135 countries (2002–2018) to test the hypothesis that Lava Jato impacts the Worldwide Governance Indicators in Brazil. The findings reveal that Lava Jato negatively affects control of corruption, the rule of law, and regulatory quality. There are signs of possible improvement in at least the corruption and the rule of law measures. This paper brings value to the criminological body of literature, notably lacking in the Global South.

scholarly journals A Review of Photocatalytic Materials for Urban NOx Remediation

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 675
Author(s):  
Hugo Savill Russell ◽  
Louise Bøge Frederickson ◽  
Ole Hertel ◽  
Thomas Ellermann ◽  
Steen Solvang Jensen
Keyword(s):  
Photocatalytic Oxidation ◽  
Urban Air Pollution ◽  
Field Trials ◽  
Urban Environments ◽  
Physical Parameters ◽  
Nox Removal ◽  
Removal Efficiencies ◽  
The Impact ◽  
By Products ◽  
Photocatalytic Materials

NOx is a pervasive pollutant in urban environments. This review assesses the current state of the art of photocatalytic oxidation materials, designed for the abatement of nitrogen oxides (NOx) in the urban environment, and typically, but not exclusively based on titanium dioxide (TiO2). Field trials with existing commercial materials, such as paints, asphalt and concrete, in a range of environments including street canyons, car parks, tunnels, highways and open streets, are considered in-depth. Lab studies containing the most recent developments in the photocatalytic materials are also summarised, as well as studies investigating the impact of physical parameters on their efficiency. It is concluded that this technology may be useful as a part of the measures used to lower urban air pollution levels, yielding ∼2% NOx removal in the immediate area around the surface, for optimised TiO2, in some cases, but is not capable of the reported high NOx removal efficiencies >20% in outdoor urban environments, and can in some cases lower air quality by releasing hazardous by-products. However, research into new material is ongoing. The reason for the mixed results in the studies reviewed, and massive range of removal efficiencies reported (from negligible and up to >80%) is mainly the large range of testing practices used. Before deployment in individual environments site-specific testing should be performed, and new standards for lab and field testing should be developed. The longevity of the materials and their potential for producing hazardous by-products should also be considered.

scholarly journals When is a Match Sufficient? A Score-based Balance Metric for the Synthetic Control Method

2020 ◽  
Vol 8 (1) ◽  
pp. 209-228
Author(s):  
Layla Parast ◽  
Priscillia Hunt ◽  
Beth Ann Griffin ◽  
David Powell
Keyword(s):  
Los Angeles ◽  
Control Method ◽  
Control Unit ◽  
Treated Group ◽  
Control Group ◽  
Synthetic Control ◽  
Donor Pool ◽  
Synthetic Control Method ◽  
The Mean ◽  
The Impact

AbstractIn some applications, researchers using the synthetic control method (SCM) to evaluate the effect of a policy may struggle to determine whether they have identified a “good match” between the control group and treated group. In this paper, we demonstrate the utility of the mean and maximum Absolute Standardized Mean Difference (ASMD) as a test of balance between a synthetic control unit and treated unit, and provide guidance on what constitutes a poor fit when using a synthetic control. We explore and compare other potential metrics using a simulation study. We provide an application of our proposed balance metric to the 2013 Los Angeles (LA) Firearm Study [9]. Using Uniform Crime Report data, we apply the SCM to obtain a counterfactual for the LA firearm-related crime rate based on a weighted combination of control units in a donor pool of cities. We use this counterfactual to estimate the effect of the LA Firearm Study intervention and explore the impact of changing the donor pool and pre-intervention duration period on resulting matches and estimated effects. We demonstrate how decision-making about the quality of a synthetic control can be improved by using ASMD. The mean and max ASMD clearly differentiate between poor matches and good matches. Researchers need better guidance on what is a meaningful imbalance between synthetic control and treated groups. In addition to the use of gap plots, the proposed balance metric can provide an objective way of determining fit.

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