bluuebunny/crossref_metadata_2025 huggingface dataset:
Dessert Lithofacies Study of Fengxi Tight Oil in Qaidam Basin
Authors: Guo Delong , Zhang Li , Ma Bin , Wan Qingyang , Gao Xuejiang , He Jinpeng
Published: November 2024

Two kinds of sweet spots were deposited in the shallow-semi-deep lake subfacies during N1-N21 in Fengxi area of Qaidam Basin, but it is not clear which kind of sweet spots are dessert targets. The lithofacies of Fengxi tight oil sweet spot is analyzed from geological and engineering angles, and the optimal target of exploration and development is obtained. From the source rock quality, lithology characteristics, reservoir property, oil content and so on, the geological sweet spot analysis is carried out. The engineering dessert mainly adopts triaxial compression experiment to obtain rock mechanics parameters. Through fracturing physical model experiment, the fracture growth morphology under different geological and engineering conditions is simulated, and the law of hydraulic fracture growth is explored. The structure of algal limestone is dominated by clumps, complex fabric, poor stratification, and high fracture complexity after fracturing. The stratification of laminar lime-dolomite rock is strong, the fracture is easy to spread along the bedding after fracturing, and the fracture complexity is low. Considering the pore structure and post-compaction complexity of the reservoir, it is suggested that algae limestone should be selected as the sweet rock for exploration and development in the Fengxi tight oil area.
Application of Seismic Attribute Clustering Method Based on PCA-SOM in Identification of Paleochannels
Authors: Bian Burong
Published: November 2024

Paleochannels are crucial reservoir types in continental oil and gas fields. The P oil layer in the Sanzhao Depression of the Songliao Basin is a typical example of river-controlled delta-phase deposition. The underwater diversion channel is highly developed and serves as the primary unit of the oil and gas reservoir. The stacking of the river channel creates a complex relationship. Identifying river channels has always been a challenging aspect of predicting sweet spot reservoirs due to the thinness of the sand, fault cutting, seismic acquisition and processing noise, low-resolution constraints, and other factors. This paper proposes a method for identifying river channels by combining principal component analysis (PCA) and self-organised mapping network (SOM) with seismic attribute clustering. The aim is to address the issue of difficult identification of paleochannels. The seismic attribute set, which contains multiple types of attributes, is first dimensionality reduced using principal component analysis. Then, a few principal components that can characterise the attribute set are extracted and used as inputs to the self-organising map (SOM). This reduces the dimensionality of the training sample set and simplifies the network structure. The self-organising neural network structure is designed based on the input sample features. Training is then carried out, and the network weights are updated. Attribute clustering is performed to obtain the river identification results. The effectiveness of this method for paleochannel recognition is verified by the clear morphology of the recognised paleochannels in the Songliao Basin, their conformity to geological understanding, and their matching with drilling information.
Application of vertical seismic profile multi-component data to tight sandstone gas reservoirs
Authors: Li Qin , Li Ge , Kun Luo , Yuanzhong Chen , Jian Tang
Published: November 2024

Given the complex geological characteristics of the tight gas sandstone in the Shaximiao Formation of the Jurassic in the central Sichuan Basin, including its wide distribution, narrow width, and thin thickness, conventional surface seismic methods face significant challenges in reservoir delineation. To address this challenge, a vertical seismic profile (VSP) survey was conducted in the region in 2022, along with the simultaneous collection of 3D3C surface seismic data. This article mainly elaborates on a case study of using multi-component VSP technology to delineate tight sandstone gas reservoirs. By comparing the processed VSP imaging volume with the surface seismic imaging volume, it was discovered that the frequency width of the VSP image was 8 to 12 Hz higher than that of the surface seismic image. Utilizing the multi-component information in VSP data, it is feasible to more precisely delineate tight gas sandstones, thereby reducing the uncertainty of data interpretation. Based on the conventional data interpretation of these images, an innovative application suggests using the centroid frequency ratio of PSv to PP waves as an indicator for tight sandstone. The results show that this attribute has high sensitivity to this type of reservoir. Combining geological, drilling, and logging data, an interpretation template was established based on VSP data to interpret 3D3C surface seismic data and propose new drilling well locations. The conclusion is that the successful application of VSP technology cannot be achieved without the integration of multiple disciplines. The combined exploration technology of multi-component VSP and 3D3C surface seismic has been demonstrated to have high application value through practical application, significantly improving the success rate of gas wells and providing effective support for the exploration and development of tight sandstone gas reservoirs.
Technical Status and Development Trends of Difficult Throttles Treatment Technology in Gas Wells
Authors: Wang Sifan
Published: November 2024

In order to promote the development of treatment technology for difficult throttles in gas wells and assist in solving the problem of gas well shutdown caused by the failure of difficult throttle treatment, this paper delves into the structural principles of preset throttles and slip-type throttles, introducing various types such as preset wire deployment and fishable throttles, preset non-wire deployment and fishable throttles, mechanical slip-type throttles, and electric throttles. It systematically analyzes the difficulties in retrieving difficult throttles, including wire breakage, fishing head breakage, deformation and breakage of slips, eccentric fishing head, non-release of inflated rubber cylinder, jamming, sand burial, scaling, fluid accumulation, falling objects underground, tubing deformation, and complex production tubing strings. Furthermore, it sequentially introduces weighted steel wire fishing treatment, coiled tubing fishing treatment technology, milling and fishing stuck throttles treatment, snubbing operation treatment technology, and well killing and workover treatment technology, which encompass punching holes in the tubing treatment technology, tubing cutting technology under pressure and sand flushing technology. The shortcomings of each treatment technique are also highlighted. Taking into account the current challenges faced in the treatment of difficult throttles, such as high cost and low efficiency in low-pressure gas wells, poor technical adaptability, and high risk of operational failure, it is pointed out that future difficult throttle processing technology should focus on two key directions. Firstly, it should aim for non-well-killing and low-cost development. Secondly, it should strive to reduce the occurrence and treatment difficulty of difficult throttles from the source design. And it provides technical references and ideas for the design of the next generation throttles.
Key Technologies for Volume Fracturing of Yingxiongling Shale Oil in the Qaidam Basi
Authors: Wan Youyu , Lin Hai , Xiong Tingsong , Zhang Yuxiang , Liu Shiduo , Wang Zhisheng , Zhao Wenkai , Guo Delong , Xie Guiqi , Feng Daqiang
Published: November 2024

The Yingxiongling shale oil in the Qaidam Basin is the preferred choice for Qinghai Oilfield to enter the field of unconventional oil and gas resources, and volume fracturing is the core technology for shale oil exploration and development. Through the analysis of the geological and engineering characteristics of the Yingxiongling shale oil, it is found that there are difficulties in volume fracturing of the Yingxiongling shale oil, such as frequent changes in vertical mechanical properties and limited vertical control range; large stress differences, making it difficult to form complex artificial fractures; difficulty in opening multiple clusters of perforation holes; high water shortage in the plateau, high mineralization of the formation backflow fluid, and difficulty in reusing the backflow fluid. By iteratively modeling three-dimensional geomechanics, a high-resolution three-dimensional geomechanical model is established to guide the optimization of volume fracturing schemes. Through the integration of geological and engineering selection and clustering, three-stage active control technology for cracks, and the dual temporary plugging process of boreholes and cracks, the targeted and complex degree of artificial crack transformation can be improved. Through the study of high salinity fracturing fluid system, it has been found that high salinity backflow fluid can replace slick water and alleviate the demand for fresh water in volume fracturing. The article analyzes the difficulties of shale oil volume fracturing and studies the formation of an effective set of key techniques for volume fracturing, achieving the goal of improving the degree and effectiveness of transformation, and providing support for the exploration and development of the Yingxiongling shale oil in the Qaidam Basin.
Research and Application of Flexible Fracturing Manifold in Volumetric fracturing
Authors: Chai Long , Bai Mingwei , Ye Sai , Che Haoyang , Yang Min
Published: November 2024

In order to solve the problems of high pressure pipe valves in Volumetrictric fracturing, such as large demand of high pressure pipe and valve parts, high pressure manifold for fracturing complex connection, fracturing pipeline connections are complex, long fracturing construction preparation period. The economy and timeliness of pipeline connection seriously affect the speed and efficiency of Volumetrictric fracturing operations. This paper designed and developed the high pressure flexible composite pipe and carried out its performance evaluation test. Combined with Volumetrictric fracturing operation conditions, supporting functional modular manifold system, overcome flexible pipeline and rigid pipeline fast connection technology, flexible fracturing manifold system was formed. Through the large-scale field application in the unconventional reservoir Volumetric fracturing field, The flexible fracturing manifold is compared with the conventional high-pressure pipe valve connection and the single pipe universal connection, the flexible fracturing manifold can reduce the use of high-pressure pipe valves by 1/3, increase the efficiency of fracturing manifold connection by 50%, and reduce the labor intensity by 50%, enables efficient, reduce high pressure manifold connection points by 70%. The timeliness and safety of fracturing manifold connections have been greatly improved. Flexible fracturing manifold fundamentally change the connection mode of Volumetrictric fracturing high-pressure manifold, and realizes the speed and efficiency of reservoir transformation.
Experimental study on oxidation characteristics of low temperature oxidation stage of thin oil in P layer in eastern Daqing Placanticline
Authors: Wu Yan , Sun Hanpeng
Published: November 2024

The eastern oilfield of Daqing Placanticline belongs to a medium low permeability oilfield as a whole, with some blocks developed earlier and in the stage of high water content and high recovery. The main oil layer is severely flooded, and the remaining oil distribution is scattered. It is difficult to improve the development effect through conventional water flooding adjustments. In order to clarify the feasibility and key parameters of thin oil fire flooding development in the eastern P reservoir of Daqing Placanticline, experimental research on low-temperature oxidation stage oxidation characteristics was conducted using typical block rock cuttings and crude oil. Complete 20 sets of experiments on the oxidation characteristics of crude oil under different temperature and pressure, 4 sets of experiments on the oxidation characteristics of crude oil under different combustion systems, and 12 sets of tests on the composition of crude oil and exhaust gas. Clarify the low-temperature oxidation characteristics of crude oil under different temperatures and pressures, determine the oxidation characteristics of crude oil under different catalytic systems, and divide the temperature range for crude oil to reach ignition, providing theoretical support for improving reservoir fuel for thin oil flooding.
Study on The Areal Sweep Efficiency and Water Breakthrough Time Prediction of Water Flooding in Carbonate Reservoirs
Authors: Na Risu , Zhang Yu , Guo Sheng , Li Changyong , Sun Futing
Published: November 2024

This study concentrates on the evaluation of areal sweep efficiency and the prediction of water breakthrough time in a representative medium-porosity, medium-high permeability thin carbonate reservoir, using the H oilfield in the Middle East as an example. Areal geological models, accounting for variations in high permeability streaks and regional heterogeneity, were established to study the impact of areal heterogeneity on the sweep coefficient and morphology of the water flooding front. The results revealed that areal heterogeneity significantly affects both the areal sweep efficiency and the morphology of the water flooding front. In models with high permeability streaks, a greater permeability ratio led to more uneven displacement in all directions, consequently, this resulted in a poorer overall development effect. Furthermore, regional heterogeneity was found to significantly impact sweep efficiency, the larger the area of relatively low permeability zones, the more severe the reduction in sweep efficiency and the overall injection production effect. A theoretical method for accurately predicting water breakthrough time was established based on the stream tube method. This method was applied to the H oilfield, which reduced the discrepancy between the predicted and actual breakthrough times, thereby confirming its feasibility. The novelty of this study lies in overcoming the limitations of the stream tube method and utilizing numerical simulation to calculate the areal sweep coefficient at the time of water breakthrough. This approach quantitatively characterized the affected streamline area, thereby enhancing the accuracy of water breakthrough time predictions. This research provides significant theoretical insights and practical references for understanding the areal sweep efficiency of thin carbonate reservoirs, predicting water breakthrough times, and optimizing injection production strategies.
Borehole Stability of Natural Gas Hydrate Reservoirs
Authors: Yan Chuanliang , Zhang Zhe , He Yufa , Tian Zheng , Cheng Yuanfang
Published: November 2024

The decomposition of natural gas hydrate (NGH) due to long-term drilling may decrease the strength of reservoirs and increase the borehole failure risk. Meanwhile, the creep properties of NGH reservoirs also may give rise to engineering problems including borehole shrinkage and jamming of drilling tools in the late stage of drilling, which seriously impairs the drilling safety. A thermal-fluid-solid multi-field coupling model considering the decomposition kinetics of NGH and creep properties of reservoirs was established to explore the influence mechanism of NGH decomposition and creep properties of hydrate-bearing sediments on mechanical behaviors of boreholes. In addition, influences of drilling parameters and geomechanical properties of reservoirs on borehole stability in the drilling process of NGH reservoirs were analyzed. Research results show that creep properties of NGH deposits causes homogenization of stress distribution in different directions of NGH reservoirs around boreholes, transition of plastic zones around boreholes to a round shape, and possibly overall borehole collapse. As the horizontal geostress becomes more inhomogeneous, the borehole instability risk increases; the higher the initial pore pressure of formation is, the lower the effective geostress and the lower the borehole instability risk. The research results can provide theoretical support for safe drilling of NGH reservoirs in South China Sea and promote the early commercial exploitation of NGH resources in China.
Improvement of Sonic Logging Porosity Calculation Method in South Sulige Block
Authors: He Wang , Yalan Wang , Bo Wang , Yonghui Jia , Yuan Sun , Xiao Xiang , Kaicheng Yang
Published: November 2024

South Sulige Block is a lithologic gas reservoir with low porosity and permeability, low pressure and low abundance, of which the heterogeneity is very high and pore structure is complex. Due to the influence of lithology and pore structure, the skeleton value is uncertain and it is hard to give a fixed value. It is difficult to obtain the true porosity of formation accurately by using the traditional method of calculating porosity by Wyllie formula in sonic logging. In this paper, according to the principle of sonic logging and rock response characteristics, combined with core analysis data of this area and adjacent areas, using the acoustic time and core analysis porosity regression formula to calculate porosity first, and then, according to different shale content, the corresponding shale correction is carried out for heavy shale content intervals on the basis of core regression formula, which eliminates the porosity calculation error caused by the influence of shale content. Practical application shows that the porosity calculated by this method is in good agreement with the results of core analysis, and can reflect the reservoir characteristics and production capacity of the formation more truly.
Two-stage Cementing Technology for Production Casing in Deep Reservoir of Chenghai Oilfield
Authors: Hu Jinjun , Shi Weiji , Wu Wenbing , Shen Jiyang , Li Jianglong , Shen Yayun
Published: November 2024

The whole well section cementing of production casing in 5 000 m deep reservoir of Chenghai Oilfield was faced with many difficulties, such as long sealing section, large temperature difference, serious leakage and serious cement slurry contamination caused by organic salt drilling fluid. On the basis of the stage cementing technology, the newly developed micro thixotropic cement slurry and anti-organic salt spacer were used to reduce leakage and contamination, and the double-acting stage collar was applied to reduce the risk of stage cementing tool failure. A two-stage cementing technology suitable for the development of deep reservoir in Chenghai Oilfield was formed. The cement slurry exhibits good micro thixotropic performance at 50~130 °C. The rheological properties change from thin to thick and then to thin with increasing temperature, and the difference of static shear force is no less than 12.2 Pa. The spacer shows good anti-contamination property. The thickening time of the contaminated cement slurry after mixing the spacer is more than 6 h, and the sedimentation stability of the spacer is no more than 0.04 g/cm3. The double-acting stage collar has the advantages of both mechanical and differential pressure stage collar, which can effectively reduce the risk of circulation holes not being opened or closed. The technology had been successfully applied in 2 wells in Chenghai Oilfield. During cementing operation, the stage collar worked well, there was no leakage, cement slurry contamination could be controlled, and cementing quality met needs. The technology can be further promoted and applied in the area.
Design and Test of Hydraulic Bottom Seal Fracturing Tool for Coiled Tubing
Authors: Wang Weipeng , Long Shiming , Su Minwen , Ma Yuxin , Huang Weiping
Published: November 2024

As the main tool for reservoir reconstruction of Longdong shale reservoir in Changqing Oilfield, the coiled tubing bottom seal drag-segment fracturing tool is currently in the stage of scale promotion, providing tool support for the efficient development of Longdong shale oil. However, in the process of horizontal construction with large water vertical ratio and super long horizontal section, there are construction problems such as natural depth limitation of the tool and difficulty in setting the bottom packer, which seriously affect the construction efficiency and quality. In view of the above problems, this paper carried out the development of pumped coiled tubing hydraulic bottom seal drag-segment fracturing tool. With the technical ideas of pumping cup deepening and hydraulic setting bottom packer, the hydraulic setting type bottom packer, soluble cup pumping sub and supporting tools were designed and developed. By using the method of annular pumping and tubing accompanying injection, the tail cup pumping sub was used to generate throttle and larger cup outer diameter, forming a large hydraulic traction force to carry the tool string to break the depth limit. Without applying drilling pressure, the bottom packer was set by oil injection and displacement, and the setting state was lifted and lifted after the fracturing construction, providing a reliable tool scheme for solving the above engineering problems. The indoor evaluation results show that the traction effect of the bowl pumping short joint with small displacement of water is good, the bottom packer is smooth in the setting and unpacking action at 120°C, and the sealing is reliable under 70MPa pressure. The overall test of the tool string can realize the setting and unpacking action without the intervention of drill pressure. Six well tests were carried out in the field. The pumping depth was 430m under the condition of 740L/min water pumping displacement, and the oil injection displacement was increased to 550L/min. The hydraulic setting was fast and reliable, which effectively improved the construction capacity of the coiled tubing fracturing tool in the ultra-long horizontal well, greatly shortened the time consumption of interlayer conversion, and improved the speed and efficiency significantly.
Analysis of Fracture Reason of Transmission Shaft of Screw Drilling Tool in a Certain Well
Authors: Hu Fang-ting , Zhao Mi-feng , Geng Hai-long , Long Yan , Lou Er-biao
Published: November 2024

During the drilling process of a certain well in an oil field, the transmission shaft of the screw drilling tool broke. According to research, the screw drilling tool is brand new and has been in use for only 63.5 hours, indicating early failure. The fracture of the transmission shaft of the screw drilling tool is flat and severely worn, and the fracture is located at the change in diameter. In order to analyze the causes of the tool’s failure and avoid similar accidents, this article conducted non-destructive testing, macroscopic fracture analysis, chemical composition analysis, tensile performance testing, Charpy impact testing, Brinell hardness testing, metallographic analysis, microscopic analysis, and a comprehensive analysis of the failed transmission shaft of the spiral drilling rig. Through a series of analyses, it is believed that this tool belongs to fatigue fracture. The main reason is the presence of quenching cracks in the matrix structure near the fracture surface, which does not comply with industry standards. At the same time, before the screw drilling tool was put into use in the well, the operator did not conduct a flaw detection on the transmission shaft body according to the standard, so that quenching cracks were not detected in advance. After entering the well, the transmission shaft undergoes rapid propagation of quenching cracks under variable load, ultimately leading to early fatigue failure. This article suggests that manufacturers optimize the heat treatment process of screw drilling tool transmission shafts to improve product quality and prevent quenching cracks from appearing in the body. At the same time, operators should strictly follow the standards for non-destructive testing to avoid drilling tools with quality issues from entering the well for use.
A Well-Tested Pump Card Classification and Identification Algorithm Based on Time Series Analysis Techniques
Authors: Yang Hao-lin , Wang Jing-xin , Liu Hao , Wang Shuai , Zhang Quan-xin
Published: November 2024

To accurately identify the operational conditions of oil pumping wells, promptly monitor the working status of oil wells, expedite responses to sudden pumping well accidents, and ensure orderly production at the oil extraction site, this paper introduces a time segment-based oil pumping well condition identification algorithm. This method no longer relies on drawn dynamometer cards for condition identification. Instead, it solely utilizes sensor-provided polished rod displacement and load time series, aligning more closely with the data’s intrinsic nature. The algorithm is sufficiently lightweight, highly responsive, and does not require GPU resources, making it suitable for edge deployment. Furthermore, this approach provides evidence of the time continuity and numerical continuity of time series data. Compared to traditional identification methods, this approach maintains a high level of accuracy, offers a streamlined model, and is interpretable, presenting a novel perspective for oil pumping well condition identification.
Research on an aeroengine bearing fault diagnosis method based on WMSST-CNN-BKA-LSSVM
Authors: Wei Zhihui , Liu Zhengang , Guo Zhengbo , Guo Haidong
Published: November 2024

To effectively extract the fault feature from small sample datasets and improve the accuracy of the model, an aeroengine bearing fault diagnosis method is proposed in this research based on wavelet multi-synchrosqueezed transform-convolutional neural network-black-winged kite algorithm-least squares support vector machine (WMSST-CNN-BKA-LSSVM). WMSST was used to perform modal decomposition on the collected fault data to obtain the time-frequency images. The time-frequency images were input into CNN for fault data feature extraction. The results of the CNN fully connected layer were used as input to the LSSVM, and the BKA was used to optimize the key parameters of the LSSVM to classify aeroengine bearing faults. The method was verified by aeroengine bearing test data from the Harbin Institute of Technology. The research showed that the accuracy is 99.86% when the faulty test samples are 70%, and the accuracy is 93.90% when the faulty samples are 30%. The accuracy showed the applicability of this method in small sample fault diagnosis. By comparing the method with a one-dimensional convolutional neural network (1D-CNN) and the convolutional neural network - long short-term memory (CNN-LSTM), it is found that the accuracy has been dramatically improved.
Nonuniform Bose–Einstein condensate: I. An improvement of the Gross–Pitaevskii method
Authors: Tomchenko Maksim
Published: November 2024

A nonuniform condensate is usually described by the Gross–Pitaevskii (GP) equation, which is derived with the help of the c-number ansatz

Ψ
^

(

r

,
t
)
=
Ψ
(

r

,
t
)

. Proceeding from a more accurate operator ansatz

Ψ
^

(

r

,
t
)
=

a
^

0

Ψ
(

r

,
t
)

/

N

, where N is the number of Bose particles, we find the equation

i
ℏ

∂
Ψ
(

r

,
t
)

∂
t

=
−

ℏ

2

2
m

∂

2

Ψ
(

r

,
t
)

∂

r

2

+

(
1
−

1
N

)

2
c
Ψ
(

r

,
t
)

|

Ψ
(

r

,
t
)

|

2

, which we call the GP
N
equation. It differs from the GP equation by the factor

(
1
−
1

/

N
)

. We compare the accuracy of the GP and GP
N
equations by analysing the ground state of a one-dimensional system of point bosons with repulsive interaction (c > 0) and zero boundary conditions. Both equations are solved numerically, and the system energy E and the particle density profile

ρ
(
x
)

are determined for the mean particle density

ρ
¯

=
1

, different values of N and of the coupling constant

γ
=
c

/

ρ
¯

. The solutions are compared with the exact ones obtained by the Bethe ansatz. The results show that the GP and GP
N
equations equally well describe the many-particle system (

N
≳
100

) being in the weak coupling regime (

N

−
2

≪
γ
≲
0.1

). But for the few-boson system (

N
≲
10

) with

γ
≲

N

−
2

the solutions of the GP
N
equation are in much better agreement with the exact ones. Thus, the multiplier

(
1
−
1

/

N
)

allows one to describe few-boson systems with high accuracy. This means that it is reasonable to extend the notion of Bose–Einstein condensation to few-particle systems.
Comprehensive Study of EPDM Rubber Properties: Temperature-Dependent Stiffness, Tensile Behavior and FEA Calibration
Authors: Foltuț Daniel , Vălean Estera , Șoșoi Georgiana-Iulia , Pascal Dragoș-Toader , Pospisil Jan , Buzdugan Monica
Published: November 2024

This work examines the temperature-dependent stiffness of Ethylene Propylene Diene Monomer (EPDM) rubber using tensile testing and Dynamic Mechanical Analysis (DMA). Additionally, it provides an appropriate model for Finite Element Analysis (FEA). The tensile tests indicate that EPDM has high rigidity and minimal elongation at −40°C, intermediate characteristics at 23°C, and a decrease in stiffness with rising temperature, up to 80°C. Nevertheless, a sudden rise in rigidity is seen at a temperature of 125°C, which may be ascribed to the strengthening influence of carbon black. The DMA findings confirm this pattern, demonstrating an upward trend in storage modulus and stiffness as temperature increases. At the same time, tan delta and loss modulus fall, suggesting a reduction in viscoelastic damping. The calibration of the Finite Element Analysis (FEA) model, using the Arruda-Boyce, Yeoh 3D, and Mooney-Rivlin 5-parameter models, determines that the Arruda-Boyce model is the most precise in accurately replicating the experimental data. The results indicate that the improved resistance to heat and increased rigidity of EPDM at high temperatures are affected by its material composition. However, more investigation is required to have a comprehensive understanding of the underlying processes.
Topology in a one-dimensional plasmonic crystal: the optical approach
Authors: Miranda D A , Bludov Y V , Asger Mortensen N , Peres N M R
Published: November 2024

In this paper we study the topology of the bands of a plasmonic crystal composed of graphene and of a metallic grating. Firstly, we derive a Kronig–Penney type of equation for the plasmonic bands as function of the Bloch wavevector and discuss the propagation of the surface plasmon polaritons on the polaritonic crystal using a transfer-matrix approach considering a finite relaxation time. Second, we reformulate the problem as a tight-binding model that resembles the Su–Schrieffer–Heeger (SSH) Hamiltonian, one difference being that the hopping amplitudes are, in this case, energy dependent. In possession of the tight-binding equations it is a simple task to determine the topology (value of the winding number) of the bands. This allows to determine the existense or absence of topological end modes in the system. Similarly to the SSH model, we show that there is a tunable parameter that induces topological phase transitions from trivial to non-trivial. In our case, it is the distance d between the graphene sheet and the metallic grating. We note that d is a parameter that can be easily tuned experimentally simply by controlling the thickness of the spacer between the grating and the graphene sheet. It is then experimentally feasible to engineer devices with the required topological properties. Finally, we suggest a scattering experiment allowing the observation of the topological states.
Local field potential-based brain-machine interface to inhibit epileptic seizures by spinal cord electrical stimulation
Authors: Garcia Cerqueira Erika Maria , de Medeiros Raquel Emanuela , da Silva Fiorin Fernando , de Arújo e Silva Mariane , Hypolito Lima Ramón , Azevedo Dantas André Felipe Oliveirade , Rodrigues Abner Cardoso , Delisle-Rodriguez Denis
Published: November 2024

Objective. This study proposes a closed-loop brain-machine interface (BMI) based on spinal cord stimulation to inhibit epileptic seizures, applying a semi-supervised machine learning approach that learns from Local Field Potential (LFP) patterns acquired on the pre-ictal (preceding the seizure) condition. Approach. LFP epochs from the hippocampus and motor cortex are band-pass filtered from 1 to 13 Hz, to obtain the time-frequency representation using the continuous Wavelet transform, and successively calculate the phase lock values (PLV). As a novelty, the Z-score-based PLV normalization using both modified k-means and Davies-Bouldin's measure for clustering is proposed here. Consequently, a generic seizure's detector is calibrated for detecting seizures on the normalized PLV, and enables the spinal cord stimulation for periods of 30 s in a closed-loop, while the BMI system detects seizure events. To calibrate the proposed BMI, a dataset with LFP signals recorded on five Wistar rats during basal state and epileptic crisis was used. The epileptic crisis was induced by injecting pentylenetetrazol (PTZ). Afterwards, two experiments without/with our BMI were carried out, inducing epileptic crisis by PTZ in Wistar rats. Main results. Stronger seizure events of high LFP amplitudes and long time periods were observed in the rat, when the BMI system was not used. In contrast, short-time seizure events of relative low intensity were observed in the rat, using the proposed BMI. The proposed system detected on unseen data the synchronized seizure activity in the hippocampus and motor cortex, provided stimulation appropriately, and consequently decreased seizure symptoms. Significance. Low-frequency LFP signals from the hippocampus and motor cortex, and cord spinal stimulation can be used to develop accurate closed-loop BMIs for early epileptic seizures inhibition, as an alternative treatment.
Unsupervised clustering analysis-based characterization of spatial profiles of inaccuracy in apparent diffusion coefficient values with varying acquisition plan orientation and diffusion weighting gradient direction – a large multicenter phantom study
Authors: Fedeli Luca , Benelli Matteo , Busoni Simone , Belli Giacomo , Ciccarone Antonio , Coniglio Angela , Esposito Marco , Nocetti Luca , Sghedoni Roberto , Tarducci Roberto , Altabella Luisa , Belligotti Eleonora , Bettarini Silvia , Betti Margherita , Caivano Rocchina , Carnì Marco , Chiappiniello Andrea , Cimolai Sara , Cretti Fabiola , Feliciani Giacomo , Fulcheri Christian , Gasperi Chiara , Giacometti Mara , Levrero Fabrizio , Lizio Domenico , Maieron Marta , Marzi Simona , Mascaro Lorella , Mazzocchi Silvia , Meliadò Gabriele , Morzenti Sabrina , Niespolo Alessandra , Noferini Linhsia , Oberhofer Nadia , Orsingher Laura , Quattrocchi Mariagrazia , Ricci Alessandra , Savini Alessandro , Taddeucci Adriana , Testa Claudia , Tortoli Paolo , Gobbi Gianni , Gori Cesare , Bernardi Luca , Giannelli Marco , Mazzoni Lorenzo Nicola ,   For the Italian Association of Medical and Health Physics (AIFM) working group on Magnetic Resonance Quantification, Intercomparison and Quality Assurance
Published: November 2024

This large multicenter study of 37 magnetic resonance imaging scanners aimed at characterizing, for the first time, spatial profiles of inaccuracy (namely, Δ-profiles) in apparent diffusion coefficient (ADC) values with varying acquisition plan orientation and diffusion weighting gradient direction, using a statistical approach exploiting unsupervised clustering analysis. A diffusion-weighted imaging (DWI) protocol (b-value: 0–200–400–600–800–1000 s mm−2) with different combinations of acquisition plan orientation (axial/sagittal/coronal) and diffusion weighting gradient direction (anterior-posterior/left-right/feet-head) was acquired on a standard water phantom. For each acquisition setup, Δ-profiles along the 3 main orthogonal directions were characterized by fitting data with a second order polynomial function (ar
2
+ br + c). Moreover, for each Δ-profile, the maximum minus minimum of the fitting function (δ
max) was calculated. The parameters a, b, c, and δ
max showed some significant variations between scanner systems by different manufacturers or with different static magnetic field strengths, as well as between different acquisition/estimation setups. Unsupervised clustering analysis showed two evident clusters with significantly different values of parameter a (p < 0.0001), which can be grouped by acquisition protocol/Δ-profile direction but not scanner system. The results of ∆-profiles confirm an appreciable inter-scanner variability in ADC measurement and corroborate the importance of guarantying the reliability of ADC estimations in clinical or research studies, considering for each scanner system the specific acquisition sequence in terms of acquisition plan orientation and diffusion weighting gradient direction.
Physics-inspired machine learning detects ‘unknown unknowns’ in networks: discovering network boundaries from observable dynamics
Authors: Harsh Moshir , Vulpius Leonhard Götz , Sollich Peter
Published: November 2024

Dynamics on networks is often only partially observable in experiment, with many nodes being inaccessible or indeed the existence and properties of a larger unobserved network being unknown. This limits our ability to reconstruct the topology of the network and the strength of the interactions among even the observed nodes. Here, we show how machine learning inspired by physics can be utilized on noisy time series of such partially observed networks to determine which nodes of the observed part of a network form its boundary, i.e. have significant interactions with the unobserved part. This opens a route to reliable network reconstruction. We develop the method for arbitrary network dynamics and topologies and demonstrate it on a broad range of dynamics including non-linear coupled oscillators and chaotic attractors. Beyond these we focus in particular on biochemical reaction networks, where we apply the approach to the dynamics of the epidermal growth factor receptor (EGFR) network and show that it works even for substantial noise levels.
Associated varieties of minimal highest weight modules
Authors: Bai Zhanqiang , Ma Jia-Jun , Xiao Wei , Xie Xun
Published: November 2024

Let

g

\mathfrak {g}

be a complex simple Lie algebra. A simple

g

\mathfrak {g}

-module is called minimal if the associated variety of its annihilator ideal coincides with the closure of the minimal nilpotent coadjoint orbit. The main result of this paper is a classification of minimal highest weight modules for

g

\mathfrak {g}

. This classification extends the work of Joseph [Ann. Sci. École Norm. Sup. (4) 31 (1998), 17–45], which focused on categorizing minimal highest weight modules annihilated by completely prime ideals. Furthermore, we have determined the associated varieties of these modules. In other words, we have identified all possible weak quantizations of minimal orbital varieties.
Max Weber and W. E. B. Du Bois
Authors: McAuley Christopher A
Published: November 2024

Max Weber’s and W. E. B. Du Bois’s chance encounter at the Congress of Arts and Science in St. Louis in 1904 led to a seven months–long correspondence between the two sociological pioneers. However, after what promised to be an enduring intellectual friendship, they abruptly ended their contact and never resumed it before Weber’s death in 1920. This essay explores the possible reasons for this abandoned friendship in some of the academic work that Weber and Du Bois produced prior and subsequent to their months of contact. What emerges from such an inventory are their fundamental differences over capitalism, empire, unfree labor, and racial conflict—substantive matters that may well have played significant roles in ending their intellectual exchange.
What about Democracy?
Authors: Hanke Edith
Published: November 2024

Democracy is not a central concept in Max Weber’s academic work. As a liberal citizen, Weber campaigned in 1918/1919 for equal suffrage and a parliamentary democracy with a plebiscitary “leader.” This contribution attempts to systematically grasp Weber’s concept of democracy on the basis of four narratives. Weber’s approach is sociological: democratization is a dynamic social process that interacts with the development of political equality for citizens. Ideal typically, “democracy” means self-government and can therefore no longer be achieved by the citizens themselves in modern mass states. Democratic legitimacy is insufficiently integrated into Weber’s typology of domination. For him, democracy is not a normative concept, but a rule-based political system legitimized by the citizens. This sober concept opens up opportunities to analyze the changeability and historical-cultural diversity of democracies today. According to Weber, political decisions belong in democratically legitimized institutions, but not on the streets.
Rilke’s Crocodile Tears
Authors: Martínez Celaya Enrique
Published: November 2024

This chapter explains the interplay of human flourishing and arts in correlation with the experience of art offering what people need. It looks into human flourishing concerned with self-actualization through the optimization of experience and functioning. Moreover, some sculptures, poems, and musical compositions are detrimental to human flourishing, while other pieces of art offer banal, poppish, or amusing distractions away from the lifework that human flourishing requires. The chapter explains that human flourishing implies connection and transformation, which art depends on the condition as decoration, pamphlet of the times, and cultural currency. It presents Rainer Maria Rilke’s 1908 poem “Archaic Torso of Apollo,” which was written after Rilke’s aesthetic encounter with a sculpted headless torso.
Visual Art as Harmony and Challenge
Authors: Silver Larry
Published: November 2024

This chapter considers the notion of visual art as harmony and challenge. In the modern era of films and advertising, visual art is too easily construed as a form of momentary entertainment. Moreover, art has contributed in essential ways to the consolidation or confirmation of authority, whether political or spiritual. This chapter explains that artworks can promote social cohesion through shared beliefs, such as gendered social roles, religion, and politics. Individual and wider social connections and harmonies can be achieved through personal interactions, even sometimes quite physical encounters, with works of art. The chapter also considers the blessing and curse of a modern art museum.
Public Art and the Power of Engagement
Authors: Krause Knight Cher , Senie Harriet F
Published: November 2024

This chapter provides an overview of public art’s power of engagement. It highlights the importance of positive psychology to the practice and perception of public art, which is an ideal vehicle through which to engender engagement on both individual and group levels. The more the public is involved in and with art, the more positive the results of such durational engagement may be. The chapter explains how public art contributes to human happiness and directly enriches people’s flourishing while referencing the notions of art therapy and intellectual space. It considers the PERMA model of well-being to be essential to understanding how public art promotes human flourishing.
“Well-Being” and “Flourishing” in the Ancient Synagogue
Authors: Fine Steven
Published: November 2024

This chapter covers the notions of well-being and flourishing among the remains of Jewish visual culture from Roman antiquity. It then explores the art, vision, and experience of Holiness. The decoration and furnishing of specific synagogue remains express the theology and cosmology of specific local Jewish communities, particularly the third-century synagogue at Dura Europos in Syria, and fifth- to sixth-century synagogue remains from Israel. History is a place where factuality matters, but facts are dead without people’s own creative process. The chapter cites that history provides models for the world, both what people would like to become and what they would never be.
Evaluation of a clinical decision support alert to identify hepatic dysfunction and need for medication therapy adjustment in hospitalized patients
Authors: Nguyen Kevin B , Jacobs Scott , Tasnim Nissa , Knorr John P
Published: November 2024

Purpose

To optimize the hepatic dysfunction alert tool at our institution to identify appropriate patients and minimize irrelevant alerts.

Methods

This single-center, retrospective review included adults hospitalized over a 1-month period for whom a hepatic dysfunction alert fired for a medication order placed in the electronic health record. The existing alert determines hepatic dysfunction based on laboratory tests. The primary objective was to determine the proportion of patients with an alert that was deemed to be clinically relevant. Alerts were considered relevant if the patient had a Child-Pugh score in class B or C and were ordered a medication with a hepatic warning from FDA or LiverTox. The performance of 14 alternative models was evaluated.

Results

A total of 1,541 alerts fired for 309 patients. Of these patients, 155 were randomly selected for the analysis, and the alert was deemed relevant in 86 patients (55%). Patients with relevant alerts were more likely to have documented liver disease and worsening measures on liver function tests. Of the alternative models evaluated, a model that excluded INR and albumin resulted in a 27% decrease in the number of alerts fired, of which 73% were relevant; however, it failed to identify 30% of patients with relevant hepatic dysfunction. None of the other models performed better.

Conclusion

The existing hepatic dysfunction clinical decision support tool correctly identifies patients with relevant hepatic dysfunction only 55% of the time. Alternative models were able to improve the rate of relevant results, but not without missing patients with relevant hepatic dysfunction.
Impact of a social media post on improving an existing residency program
Authors: Choudhary Kavish , Hager David , Thoma Lynn , Fox Erin R
Published: November 2024

Purpose

A social media post prompted reflection and changes to a longstanding pharmacy residency program. Pharmacy leadership utilized consultants with expertise in pharmacy residency training to help facilitate change and introduce new ideas to tenured staff. Other health systems working to continuously improve their residency programs may benefit from our example.

The guiding principles of the changes were to align with the new harmonized residency program standards and reduce preceptor burden and potential burnout. Changes were made to the entire program’s design, including new leadership, changes to committee structure, reduced requirements for preceptors that were not required in the standards, and resident recruitment and onboarding.

Conclusion

We encourage residency programs to regularly evaluate program structure, design, and conduct to ensure alignment with the organization’s evolving priorities as well as its mission and vision.