scholarly journals Resistivity and AE Response Characteristics in the Failure Process of CGB under Uniaxial Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Tingye Qi ◽  
Guorui Feng
Keyword(s):  
Failure Process ◽  
Peak Stress ◽  
Uniaxial Loading ◽  
Energy Curve ◽  
Cumulative Energy ◽  
Response Characteristics ◽  
Before And After ◽  
The Difference ◽  
Linear Slope ◽  
The Stability

To understand the characteristics of the acoustic emission (AE) and electrical resistivity of cemented coal gangue backfill (CGB) under uniaxial compression, the variations in these characteristics at 1 day, 3 days, and 7 days are analyzed by means of a stress-strain-resistivity-AE test, and the microperformances are investigated. The research results indicate that the AE can reflect the initiation and propagation of cracks and later explain the variation of the resistivity of the specimens under the uniaxial loading. The cumulative energy curve of AE is approximately two straight lines corresponding to the peak stress, and the difference in the linear slope gradually decreased with the increasing curing time due to the lower pore solution content and the compact pore structure. The relationships between the stress and resistivity and the loading condition before and after the peak stress at different curing times were established. Therefore, it is of great significance to predict the stability of the filling body by monitoring the AE and resistivity variations of the filling body. In addition, it is possible to calculate the roof stress using the relation equation between the resistivity and stress.

scholarly journals Failure Prediction of Two Types of Rocks Based on Acoustic Emission Characteristics

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Bing Sun ◽  
Shanshan Hou ◽  
Jiehui Xie ◽  
Sheng Zeng
Keyword(s):  
Acoustic Emission ◽  
Rock Mass ◽  
Stability Analysis ◽  
Rock Burst ◽  
Uniaxial Compression ◽  
Failure Process ◽  
Energy Curve ◽  
Characteristic Parameters ◽  
Cumulative Energy ◽  
The Stability

The stability analysis of rock is an important basis to ensure the safe exploitation of underground resources and the reliable operation of space engineering. Uniaxial compression and acoustic emission (AE) tests were carried out on two common rock samples with strong rock burst tendency. The relationship between mechanical characteristics, AE characteristics, and rock burst tendency in the failure process of rock with different body types and the evolution of fractal characteristics of AE parameters were discussed. Based on the cusp mutation theory, the catastrophe model of AE characteristic parameters was established to quantify the instability mechanism of rock mass. The results show that the AE mutation rate (AEMR) of the cubic specimens increase from a low level to a high level gradually in the stable fracture stage, while that of the cylindrical specimens increase sharply to the maximum when the specimens are near failure. The AE cumulative energy curves of cubic specimens show a “step” rise, while that of cylindrical specimens show a “gradual” rise, and the rock burst process of cubic specimens is faster. The fractal dimension evolution mode of AE characteristic parameters of cubic specimens during uniaxial compression text is decline-rise-decline, while that of cylindrical specimen is decline-rise-decline-steeply rise. According to the periodic change of AE cumulative energy curve, combined with the rock failure cusp mutation model, the occurrence of rock burst can be well predicted, providing certain theoretical guidance for the stability analysis of underground engineering rock mass.

scholarly journals EFEKTIVITAS KEBIJAKAN HARGA ECERAN TERTINGGI (HET) DAN RANTAI PASOK BERAS MEDIUM DI PROVINSI LAMPUNG

2020 ◽  
Vol 8 (2) ◽  
pp. 318
Author(s):  
Nadya Putri ◽  
Raden Hanung Ismono ◽  
Ktut Murniati
Keyword(s):  
Marketing Channels ◽  
Retail Price ◽  
Price Difference ◽  
Before And After ◽  
Qualitative Descriptive ◽  
The Difference ◽  
Rice Policy ◽  
The Government ◽  
The Stability ◽  
Descriptive Method

Indonesia is a country that consumes and produces rice, so rice is a primary need in Indonesia. The government stipulates the highest retail price (HET) of rice policy to maintain the stability of rice price. The purposes of this study are to fin out the effectiveness of rice HET policy in Lampung Province, to analyze the impacts of thepolicy stipulation, and to find out the difference between medium rice supply chains before and after the HET Policy. This research uses quantitative and qualitative descriptive method. Data collection techniques used were interviews using questionnaires and also observation. The results of this study were the policy of medium rice HET has not been effectively implemented Lampung Province with price difference of Rp1.663,00. This caused no impact on the farmers, distributors, retail traders, and consumers. In the previous study, the medium rice supply chain flow in Lampung Province was infour marketing channels while in the current study was in six marketing channels.Keywords: effectiviness, HET, rice, supply

Fracability evaluation of lacustrine shale by integrating brittleness and fracture toughness

2019 ◽  
Vol 7 (2) ◽  
pp. T363-T372
Author(s):  
Cheng Huang ◽  
Chao Yang ◽  
Feng Shen
Keyword(s):  
Fracture Toughness ◽  
Plastic Strain ◽  
Strain Energy ◽  
Evaluation Method ◽  
Peak Stress ◽  
Brittleness Index ◽  
Before And After ◽  
Lacustrine Shale ◽  
The Difference ◽  
The Impact

Rock brittleness and fracture toughness are important parameters for evaluating rock fracability. The stress-strain curves indicate that the lacustrine shale is strongly brittle. Brittle failure occurs rapidly when the stress of the lacustrine shale reaches its peak value. In addition, the lacustrine shale has different plastic strains before and after peak stress; this can relax the stress concentration of the crack tips. Therefore, the plastic strain that occurs before and after the peak stress can cause decreasing brittleness, which can be used to distinguish the brittleness and fracability in the formation of the lacustrine shale clearly. Moreover, this further enlarges the difference in the brittleness index. Based on the influence of plastic strain on brittleness, we have developed a new brittleness evaluation method that uses the ratio of linear elastic strain energy to the total strain energy before complete rock failure, which can indicate the difference of the lacustrine shale clearly. Fracture toughness is another important parameter that impacts the fracture extension and influences fracability. Based on the impact of brittleness and fracture toughness on the fracability, we have developed a new fracability evaluation method. The brittleness index increases with increases in the quartz content, and it decreases with increases in the albite feldspar and calcite contents. The fracture toughness decreases with increases in the quartz and clay contents, and it increases with increases in the siderite content. In addition, we established an empirical formula that can evaluate the brittleness index and the fracture toughness using mineral contents obtained from elemental logging. Using the new fracability evaluation method to optimize the fracturing stage, the preliminary field test indicates that the new approach was effective in the lacustrine shale formation.

Evaluation of the Stability of the Subjects with Anterior Cruciate Injuries Reconstruction

2020 ◽  
Author(s):  
Hossein Akbari Aghdam ◽  
Mahsa Kavyani ◽  
Maryam Bosak ◽  
Mohammad Taghi Karimi ◽  
Mehdi Motififard
Keyword(s):  
Acl Reconstruction ◽  
Postural Stability ◽  
Center Of Pressure ◽  
Mean Value ◽  
P Value ◽  
Before And After ◽  
The Mean ◽  
The Difference ◽  
Anterior Cruciate ◽  
The Stability

AbstractAnterior cruciate ligament (ACL) is the most frequently injured ligament in the knee and is often injured during sport-related activities. ACL injuries influence the abilities of the subjects during standing and walking. Although early surgical intervention is preferred treatment for the majority of knee surgeons, the effect of this approach on postural stability of patients is not fully understood. Therefore, the aim of this study was to determine the difference between stability of ACL-reconstructed subjects before and after surgery. A group of 15 consecutive ACL injured patients participated in this study. Postural stability of the patients was evaluated 1 week before and 6 months after surgery (ACL reconstruction with hamstring autograft). A Kistler force plate was used to evaluate center of pressure (COP) sway during quiet standing. The mean values of the COP parameters were obtained in pre and postsurgery conditions. Paired sample t-test was used to evaluate the difference between the stability parameters of the two conditions. The significant point was set at 0.05. The mean value of path length of COP velocity in mediolateral (ML) direction was 1,485.57 ± 479.42 mm and 2,641.33 ± 996.26 mm before and after surgery, respectively (p-value = 0.01). Although the mean value of COP velocity in anteroposterior and ML directions increased after surgery, the difference was only significant for velocity in ML direction (p-value = 0.049). The results of this study showed that the standing stability of those with ACL reconstruction decreased significantly after ACL reconstruction, which may be due to the effects of the surgery on sensory mechanism of ACL and inability of patients to return to their previous deep sense perception and knee proprioception.

Dynamic High-Field MR Imaging in Experimental Porcine Acute Pancreatitis

1995 ◽  
Vol 36 (2) ◽  
pp. 182-187 ◽  
Author(s):  
A. Piironen ◽  
R. Kivisaari ◽  
P. Pitkäranta ◽  
V.-P. Poutanen ◽  
P. Laippala ◽  
...  
Keyword(s):  
Acute Pancreatitis ◽  
Mr Imaging ◽  
High Field ◽  
Spin Echo ◽  
Flip Angle ◽  
Significant Difference ◽  
Before And After ◽  
The Difference ◽  
The Stability ◽  
Signal Intensities

The effects of acute pancreatitis on MR imaging signal intensities (SIs) were determined in an experimental study at 1.0 T. Oedematous pancreatitis was induced in 9 piglets and haemorrhagic pancreatitis in 11 piglets. Each animal served as its own control for MR imaging before and after induction of pancreatitis. T1-weighted spin echo (450/15 ms) and dynamic turbo FLASH (flip angle 8°) sequences were used without contrast medium in testing the stability of the SI measurements. There was no significant difference in the SI-versus-time curves of the pancreas in piglets with oedematous and haemorrhagic pancreatitis. However, the difference in mean SIs between healthy and diseased piglets was significant. Thus, although non-contrast MR may be useful in the diagnosis of acute pancreatitis, it does not distinguish between oedematous and haemorrhagic pancreatitis.

scholarly journals Effect of Different Dimensions of Test Samples on the Volumetric Change Assessment Of Endodontic Materials

2021 ◽  
Vol 32 (1) ◽  
pp. 42-47
Author(s):  
Fernanda Ferrari Esteves Torres ◽  
Juliane Maria Guerreiro-Tanomaru ◽  
Jader Camilo Pinto ◽  
Mario Tanomaru-Filho
Keyword(s):  
Morphological Changes ◽  
Micro Ct ◽  
Volume Loss ◽  
Micro Computed Tomography ◽  
Volumetric Change ◽  
Before And After ◽  
Different Dimensions ◽  
The Difference ◽  
The Stability ◽  
Different Diameters

Abstract New methodologies using micro-CT to evaluate solubility besides dimensional and morphological changes of endodontic materials are proposed. However, there is no standardization in the methods. The aim of this study was to assess the effect of different dimensions of test samples on volumetric change evaluation of different endodontic materials. AH Plus, FillCanal and Sealapex root canal sealers, Biodentine, IRM and MTA root-end filling cements were used in the tests. Samples of each material with a thickness of 1.5 mm and different diameters were manufactured: 6.3, 7.75, and 9.0 mm. The samples were scanned in micro-computed tomography (micro-CT) after setting and after 7 days of immersion in distilled water. The volumetric change was evaluated by means of the difference in the total volume of the specimens before and after immersion. Data were submitted to ANOVA and Tukey tests (p<0.05). The size of the samples did not affect the percentage of volumetric change of the materials (p>0.05). All sample sizes had greater volume loss for Sealapex among the sealers and Biodentine for the cements (p<0.05). In conclusion, Biodentine and Sealapex had the highest volume loss after immersion. Samples with 1.5 mm thickness, and diameters ranging between 6.3 and 9.0 mm can be used to assess the stability of endodontic materials using micro-CT without affecting the percentage of volumetric change.

scholarly journals Sudut Tenang Tanah Pasir-Lempung Pada Kondisi Runtuh

2020 ◽  
Vol 4 (2) ◽  
pp. 161-171
Author(s):  
Anto Budi Listyawan ◽  
Renaningsih Renaningsih ◽  
Qunik Wiqoyah ◽  
Aditya Galih Pradana
Keyword(s):  
Soil Layer ◽  
Angle Of Repose ◽  
Beach Sand ◽  
Merapi Volcano ◽  
Fine Grain ◽  
Before And After ◽  
The Difference ◽  
Failure Conditions ◽  
The Stability ◽  
External Forces

The soil layer is the combination of many types as well as the soil in the slope area. The soil in the slope is frequently a mixture of clay and sand. The stability of slope becomes dominantly an issue in the geotechnical engineering area. The collapse of the slope occurs because the gravity of external forces is exceeding the shear strength of the soil. The recent research develops the apparatus to determine the angle of repose of the sand-clay soil in the failure conditions. Sandy soil is taken from Beach and Merapi volcano. The clay added into the sand in the proportion of 0%, 5%, 10%, 15%, 20%, 25%, and 30%. The experiment is conducted by taking the height of the falling material of 15cm, 25cm, and 35 cm. Adding 0% to 15% clay brings the sand into SP Category, then adding 20%-30% makes the sand in the SC category. The Modulus if a fine grain of sand beach is smaller than Merapi sand. As the percentage of clay added to the sand higher, the difference of angle of repose of Merapi sand before and after failure is getting smaller, but it is not the case in Beach sand. The percentage of loss of volume of Merapi sand after failure is also going down as the portion of clay higher. The loss of volume of Beach sand added by clay is getting higher in failure condition..

scholarly journals The electrophoretic mobility of normal and leukaemic cells of mice

1968 ◽  
Vol 107 (4) ◽  
pp. 549-557 ◽  
Author(s):  
G. M. W. Cook ◽  
W. Jacobson
Keyword(s):  
Sialic Acid ◽  
Malignant Cell ◽  
Carboxyl Group ◽  
Malignant Cells ◽  
Acidic Group ◽  
Before And After ◽  
Leukaemic Cells ◽  
Lymph Node Cells ◽  
The Difference ◽  
The Stability

1. The pH–mobility relationships for saline-washed cells from a mouse strain of acute lymphoblastic leukaemia were examined before and after treatment with lower aldehydes, diazomethane and neuraminidase (EC 3.2.1.18). 2. The content of sialic acid released into the supernatant fluid of neuraminidase-treated cells was measured. 3. The stability of the charge-determining structures to temporary changes in environment (pH and ionic strength) was established. 4. Similar measurements were made on lymph-node cells obtained from non-leukaemic mice (a resistant and a leukaemia-susceptible strain were examined). 5. It is deduced that both the malignant and the non-malignant cell possess two dissociable acid functions at the cell surface, a carboxyl group of sialic acid and another acidic group(s), probably carboxyl, of pK 3·0–4·5. The malignant cells, however, have a basic dissociable function not present in the non-malignant types. 6. Suggestions are made as to how the difference in surface chemistry may be related to the problem of malignancy.

scholarly journals Changes in bowel sounds of inpatients undergo general anesthesia

2020 ◽  
Author(s):  
Guojing Wang ◽  
Mingjun Wang ◽  
Hongyun Liu ◽  
Suping Zhao ◽  
Lu Liu ◽  
...  
Keyword(s):  
General Anesthesia ◽  
Intestinal Function ◽  
Bowel Sounds ◽  
Significant Difference ◽  
Before And After ◽  
Degree Of Stability ◽  
Characteristic Values ◽  
The Difference ◽  
The Stability ◽  
Postoperative Feeding

Abstract Background: General anesthesia can affect intestinal function, but there is no objective and effective indicator to evaluate the inhibition and recovery of intestinal function. The main objective of this study is to assess whether bowel sounds (BSs) change before and after general anesthesia, then it can be explained that the BS can be an effective indicator of intestinal function. Methods: We randomly selected 26 inpatients and collected three sets of 5-minute continuous BSs before operation (Pre-op), after operation (Pro-op) and three hours after operation(3h-Pro-op) separately for each patient. The data were de-noised with adaptive filtering and wavelet threshold denoising, and processed with fractal dimension to identify the effective bowel sounds (EBSs). Then the linear and nonlinear characteristic values (CVs) of each EBS were extracted and paired t -test and rank-sum test were used to evaluate the changes of the BSs after general anesthesia. Results: For the difference between Pre-op and Pro-op, as well as between Pro-op and 3h-Pro-op, there are statistical differences ( p <0.05). Specifically, the linear CVs that can reflect the occurrence frequency, overall energy and overall duration of EBSs and the nonlinear CVs that can reflect the dispersion degree of stability and complexity of EBSs were statistically significant. However, there is no statistical difference in the CVs reflecting the energy and duration, as well as the stability and complexity of locally EBSs ( p >0.05). Also, there is no statistically significant difference between all the characteristic values between Pre-op and 3h-Pro-op ( p >0.05). Conclusion: The BSs change after general anesthesia. Furthermore, the BSs are weakened after general anesthesia and recovered to the state before general anesthesia three hours later. Therefore, the BS can be an indicator of intestinal function under general anesthesia, so as to provide guidance for postoperative feeding , which is of great clinical significance.

scholarly journals Chemical Binding of Chitosan and Chitosan Nanoparticles onto Oxidized Cellulose

2015 ◽  
Vol 10 (2) ◽  
pp. 155892501501000 ◽  
Author(s):  
Olivera Sauperl ◽  
Mirjana Kostic ◽  
Jovana Milanovic ◽  
Lidija Fras Zemljic
Keyword(s):  
Chitosan Nanoparticles ◽  
Gravimetric Method ◽  
Fiber Surface ◽  
Oxidized Cellulose ◽  
Amino Groups ◽  
Before And After ◽  
The Difference ◽  
The Stability ◽  
Aldehyde Groups ◽  
The Masses

The aim of this study was to analyze binding of chitosan and chitosan nanoparticles onto cellulose via oxidized cellulose. The ability of chitosan and chitosan nanoparticles to be adsorbed onto surfaces was determined by the use of the XPS spectroscopy which provided information about chemical composition of the fiber surface. On the other hand, the gravimetric method was also used by which the amount of chitosan and chitosan nanoparticles bounded onto surface was calculated based on the difference in masses before and after functionalization. The most important was to study the influence of aldehyde groups on the stability of chitosan binding onto cellulose. Thus, desorption of chitosan/chitosan nanoparticles from the fiber surfaces was evaluated by the presence of total nitrogen (TN) in desorption bath as well as by polyelectrolyte titrations. Together with these two methods, desorption was evaluated also by gravimetric method, where the extent of desorption was evaluated on the basis of the differences in the masses of fibers before and after desorption. It is concluded that the chitosan and chitosan nanoparticles are more efficiently bounded onto oxidized cellulose in comparison with the non-oxidized (reference) ones. Despite the binding of the positively-charged amino groups with the negative groups of cellulose and consequently smaller amount of available/residual protonated amino groups that are responsible for bioactivity, such functionalized fibers are still specifically antimicrobial.

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