期刊文献+
共找到1,820篇文章
< 1 2 91 >
每页显示 20 50 100
Effect of negative mood,serum inflammatory factors,miR-155,and brain-derived neurotrophic factor
1
作者 Qi Zhang Yue Zhao Guang-Yu Cheng 《World Journal of Psychiatry》 2025年第2期85-91,共7页
BACKGROUND Abdominal postoperative patients are susceptible to postoperative depression resulting from pain and stress,which can hinder their rehabilitation.Acupuncture has shown potential to relieve this condition.AI... BACKGROUND Abdominal postoperative patients are susceptible to postoperative depression resulting from pain and stress,which can hinder their rehabilitation.Acupuncture has shown potential to relieve this condition.AIM To analyze the mechanism by which acupuncture relieves postoperative depression in patients post-abdominal surgery.METHODS Abdominal postoperative patients with depression between January 2015 and December 2023 at the First Affiliated Hospital of Heilongjiang University of Chinese Medicine were enrolled.Patients were divided into two groups using the random throwing method:Observation(250 cases,fluoxetine hydrochloride+acupuncture treatment)and control(250 cases,fluoxetine hydrochloride treatment).Changes in negative emotions Hamilton Depression Scale 24,serum inflammatory factors[tumor necrosis factorα,interleukin(IL)-1β,IL-6],miR-155 expression levels,and BDNF levels were assessed.RESULTS Significant improvements were observed in the observation group compared to the control group in all assessed parameters after six weeks(P<0.05).This suggests that the combination of fluoxetine hydrochloride and acupuncture may be more effective in managing postoperative depression than medication alone.CONCLUSION Acupuncture complies with the principle of traditional Chinese medicine syndrome differentiation and ensures the pertinence and effectiveness of treatment.In addition,it not only actively improves depressive symptoms but also effectively regulates the serum level of inflammatory factors. 展开更多
关键词 Syndrome differentiation acupuncture Abdominal surgery DEPRESSION negative mood Serum inflammatory factor Tiny RNA-155
下载PDF
Systemic treatment strategies for triple-negative breast cancer 被引量:19
2
作者 Budhi Singh Yadav Suresh C Sharma +1 位作者 Priyanka Chanana Swaty Jhamb 《World Journal of Clinical Oncology》 CAS 2014年第2期125-133,共9页
Triple-negative breast cancer(TNBC) is defined by the lack of immunohistochemical expression of the estrogen and progesterone receptors and human epidermal growth factor receptor 2(EGFR2). Most TNBC has a basal-like m... Triple-negative breast cancer(TNBC) is defined by the lack of immunohistochemical expression of the estrogen and progesterone receptors and human epidermal growth factor receptor 2(EGFR2). Most TNBC has a basal-like molecular phenotype by gene expression profiling and shares clinical and pathological features with hereditary BRCA1 related breast cancers. This review evaluates the activity of available chemotherapy and targeted agents in TNBC. A systematic review of PubM ed and conference databases was carried out to identify randomised clinical trials reporting outcomes in women with TNBC treated with chemotherapy and targeted agents. Our review identified TNBC studies of chemotherapy and targeted agents with different mechanisms of action, including induction of synthetic lethality and inhibition of angiogenesis, growth and survival pathways. TNBC is sensitive to taxanes and anthracyclins. Platinum agents are effective in TNBC patients with BRCA1 mutation, either alone or in combination with poly adenosine diphosphate polymerase 1 inhibitors. Combinations of ixabepilone and capecitabine have added to progression-free survival(PFS) without survival benefit in metastatic TNBC. Antiangiogenic agents, tyrosine kinase inhibitors and EGFR inhibitorsin combination with chemotherapy produced only modest gains in PFS and had little impact on survival. TNBC subgroups respond differentially to specific targeted agents. In future, the treatment needs to be tailored for a specific patient, depending on the molecular characteristics of their malignancy. TNBC being a chemosensitive entity, combination with targeted agents have not produced substantial improvements in outcomes. Appropriate patient selection with rationale combinations of targeted agents is needed for success. 展开更多
关键词 BREAST cancer Triple negative BASAL like BRCA1 Poly(ADP-ribose)polymerase 1 TARGETED therapy Chemotherapy
下载PDF
Improving the performance of conventional base isolation systems by an external variable negative stiffness device under near-fault and long-period ground motions 被引量:8
3
作者 Sandhya Nepal Masato Saitoh 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2020年第4期985-1003,共19页
Recent studies have shown that base-isolated objects with long fundamental natural periods are highly influenced by long-period earthquakes. These long-period waves result in large displacements for isolators, possibl... Recent studies have shown that base-isolated objects with long fundamental natural periods are highly influenced by long-period earthquakes. These long-period waves result in large displacements for isolators, possibly leading to exceedance of the allowable displacement limits. Conventional isolation systems, in general, fail to resist such large displacements. This has prompted the need to modify conventional base isolation systems. The current work focuses on the development of an external device, comprising a unit of negative and positive springs, for improving the performance of conventional base isolation systems. This unit accelerates the change in the stiffness of the isolation system where the stiffness of the positive spring varies linearly in terms of the displacement response of the isolated objects. The target objects of the present study are small structures such as computer servers, sensitive instruments and machinery. Numerical studies show that the increase in the damping of the system and the slope of the linear function is effective in reducing the displacement response. An optimal range of damping values and slope, satisfying the stability condition and the allowable limits of both displacement and acceleration responses when the system is subjected to near-fault and long-period ground motions simultaneously, is proposed. 展开更多
关键词 base isolation near-fault earthquakes long-period earthquakes negative stiffness variable stiffness
下载PDF
Asymmetric Fuzzy Control of a Positive and Negative Pneumatic Pressure Servo System 被引量:3
4
作者 Gang Yang Jing-Min Du +1 位作者 Xiao-Yun Fu Bao-Ren Li 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第6期1438-1446,共9页
The pneumatic pressure control systems have been used in some fields. However, the researches on pneumatic pressure control mainly focus on constant pressure regulation. Poor dynamic characteristics and strong nonline... The pneumatic pressure control systems have been used in some fields. However, the researches on pneumatic pressure control mainly focus on constant pressure regulation. Poor dynamic characteristics and strong nonlinearity of such systems limit its application in the field of pressure tracking control. In order to meet the demand of generating dynamic pressure signal in the application of the hardware-in-the-loop simulation of aerospace engineering, a positive and negative pneumatic pressure servo system is provided to implement dynamic adjustment of sealed chamber pressure. A mathematical model is established with simulation and experiment being implemented afterwards to discuss the characteristics of the system, which shows serious asymmetry in the process of charging and discharging. Based on the analysis of the system dynamics, a fuzzy proportional integral derivative (PID) controller with asymmetric fuzzy compensator is proposed. Different from conventional adjusting mecha- nisms employing the error and change in error of the controlled variable as input parameters, the current cham- ber pressure and charging or discharging state are chosen as inputs of the compensator, which improves adaptability. To verify the effectiveness and performance of the pro- posed controller, the comparison experiments tracking sinusoidal and square wave commands are conducted. Experimental results show that the proposed controller can obtain better dynamic performance and relatively consis- tent control performance across the scope of work (2-140 kPa). The research proposes a fuzzy control method to overcome asymmetry and enhance adaptability for the positive and negative pneumatic pressure servo system. 展开更多
关键词 Pneumatic pressure control system Positiveand negative pressure Asymmetric control Fuzzy control
下载PDF
Fuze batterytest system based on negative delay
5
作者 郑凤芹 谢锐 《Journal of Measurement Science and Instrumentation》 CAS 2014年第1期21-24,共4页
The paper studies a cycle storage system with fixed capacity to monitor fuze battery's working voltage and noise,solving the problems of small capacity and low sample frequency.A 4 MB cycle sampling space is designed... The paper studies a cycle storage system with fixed capacity to monitor fuze battery's working voltage and noise,solving the problems of small capacity and low sample frequency.A 4 MB cycle sampling space is designed by adopting the negative delay technology,which implements the function of recording 4 MB data before triggered and then sequentially recording 50 MB data to ensure that the host computer recovers the voltage and noise data correctly and effectively.Two pieces of Flash work alternately to avoid the time conflict between commands programming and data writing.This method can make efficient use of storage space,recording the information before triggered,therefore it ensures the reliability and validity of the measured data. 展开更多
关键词 fuze battery negative delay storage measurement
下载PDF
Mean platelet volume as a novel predictor of systematic inflammatory response in cirrhotic patients with culturenegative neutrocytic ascites 被引量:2
6
作者 Marisol Galvez-Martinez Alfredo I Servin-Caamano +3 位作者 Eduardo Perez-Torres Francisco Salas-Gordillo Xaira Rivera-Gutierrez Fatima Higuera-de la Tijera 《World Journal of Hepatology》 CAS 2015年第7期1001-1006,共6页
AIM: To identify a mean platelet volume(MPV) cutoff value which should be able to predict the presence of bacterial infection.METHODS: An observational, analytic, retrospective study. We evaluated medical records of c... AIM: To identify a mean platelet volume(MPV) cutoff value which should be able to predict the presence of bacterial infection.METHODS: An observational, analytic, retrospective study. We evaluated medical records of cirrhotic patients who were hospitalized from January 2012 to January 2014 at the Gastroenterology Department of "Hospital General de México Dr. Eduardo Liceaga", we included 51 cirrhotic patients with ascites fluid infection(AFI), and 50 non-infected cirrhotic patients as control group. Receiver operator characteristic curves were used to identify the best cutoff value of several parameters from hematic cytometry, including MPV, to predict the presence of ascites fluid infection.RESULTS: Of the 51 cases with AFI, 48 patients(94.1%) had culture-negative neutrocytic ascites(CNNA), 2(3.9%) had bacterial ascites, and one(2%)had spontaneous bacterial peritonitis. Infected patients had greater count of leucocytes and polymorphonuclear cells, greater levels of MPV and cardiac frequency(P < 0.0001), and lower mean arterial pressure compared with non-infected patients(P = 0.009). Leucocytes, polymorphonuclear count, MPV and cardiac frequency resulted to be good or very good predictive variables of presence of AFI in cirrhotic patients(area under the receiving operating characteristic > 0.80). A cutoff MPV value of 8.3 fl was the best to discriminate between cirrhotic patients with AFI and those without infection. CONCLUSION: Our results support that MPV can be an useful predictor of systemic inflammatory response syndrome in cirrhotic patients with AFI, particularly CNNA. 展开更多
关键词 Mean platelet volume CIRRHOSIS Ascites fluid infection Culture negative neutrocytic ascites systemic inflammatory response
下载PDF
Airtight negative pressure dust-control technology and application of transpersite in the coal conveyer belt system 被引量:2
7
作者 马云东 贾惠艳 张大明 《Journal of Coal Science & Engineering(China)》 2008年第4期562-566,共5页
Presented a new coal dust control program that was airtight negative pressure dust-control technology at the transpersite,combining with analysis with the movement of air currents and numerical simulation of gas-solid... Presented a new coal dust control program that was airtight negative pressure dust-control technology at the transpersite,combining with analysis with the movement of air currents and numerical simulation of gas-solid flow at the transpersite,and proved the mechanism of precipitation and proliferation for coal dust-controlt in theory.The technol- ogy has made good economic results at the Heidaigou Clean Plant,not only dust concen- tration control within 10 mg/m^3 to the work site,but also substantial energy savings and cost savings. 展开更多
关键词 coal conveyer belt system transpersite DUST airtight negative pressure dust-control
下载PDF
Dynamics of 1D mass–spring system with a negative stiffness spring realized by magnets: Theoretical and experimental study 被引量:4
8
作者 Akintoye Olumide Oyelade Ziwei Wang Gengkai Hu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2017年第1期17-21,共5页
Realization of negative stiffness (NS) in damping low frequency acoustic and mechanical vibration is relevant in engineering applications. In this work, assemblage of two repelling magnets was used to produce negati... Realization of negative stiffness (NS) in damping low frequency acoustic and mechanical vibration is relevant in engineering applications. In this work, assemblage of two repelling magnets was used to produce negative magnetic spring (NMS). A mass-spring system with NMS is experimented where the free and forced vibrations of the system are examined. The anti-phase movement is observed due to the presence of proposed NMS, confirming the analytical solution. We further showed the dynamics of the system containing NS spring could also be derived from Hamilton's principle. 展开更多
关键词 negative stiffness Magnets Interaction
下载PDF
Negative Haloes and Geochemical Field Systems of Hydrothermal Deposits 被引量:1
9
作者 Ji Kejian, Wang Liben, Lu Fengxiang, Wang Wuyi and Zhang Jianhua Institute of Mineral Deposits, Chinese Academy of Geological Sciences, Beijing 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1993年第2期195-209,共15页
Primary haloes of hydrothermal deposits were previously considered as positive haloes. Although it has been recently suggested that primary haloes incude positive and negative ones, almost all the research work on pri... Primary haloes of hydrothermal deposits were previously considered as positive haloes. Although it has been recently suggested that primary haloes incude positive and negative ones, almost all the research work on primary haloes has still focused on positive haloes for various reasons. In order to understand the source of ore substances a number of large hydrothermal deposits related to magmatism including porphyry, skarn and vein type deposits have been studied. It has been found that negative haloes exist on the peripheries of positive haloes of a mineral deposit. On the basis of the study the authors propose the concept of the geochemical field system of ore-forming elements of hydrotherreal deposits, i. e., with the orebody as the centre outwards there occur the mineralized field, positive halo field, depleted field and background field successively. 展开更多
关键词 hydrothermal deposit negative halo geochemical field system
下载PDF
Influence of Negative Pressure Gradient on Pressure Distribution and Gas-Solid Flow Pattern of Solid Feed Systems 被引量:1
10
作者 Zhang Meiju Pan Feng +2 位作者 Shao Guoqiang Ge Yu Zhang Lei 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2018年第2期104-110,共7页
A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid ... A series of experiments on a solid feed system was performed to investigate the effect of negative pressure gradient on the gas-solid flow pattern and hydrodynamic characteristics.Based on the non-fluidized gas-solid two phase flow and particulate mechanics in the standpipe,a method for predicting the pressure of the air passing through the recycle chamber and the pressure drop through the loop seal slit in these systems is also presented.The predicted pressure profile along the negative pressure gradient from the proposed model exhibits a good agreement with the experimental data.The experimental data show that the gas flow in the standpipe is always upward in the negative pressure gradients,while the direction ofthe superficial gas velocity through the recycle chamber of the loop seal does not affect the pressure drop in standpipe.It increases with an increasing negative pressure gradient. 展开更多
关键词 fuidized bed solid feedsystem negative pressure gradient gas-solid fow pattern
下载PDF
Systematic review of the negative pressure wound therapy in kidney transplant recipients 被引量:1
11
作者 Badri Man Shrestha 《World Journal of Transplantation》 2016年第4期767-773,共7页
AIM To review negative pressure wound therapy(NPWT) as animportant addition to the conventional methods of wound management.METHODS A systematic review, performed by searching the PubM ed, EMBASE and Cochrane Library ... AIM To review negative pressure wound therapy(NPWT) as animportant addition to the conventional methods of wound management.METHODS A systematic review, performed by searching the PubM ed, EMBASE and Cochrane Library databases, showed 11 case reports comprising a total of 22 kidney transplantation(KT) patients(range, 1 to 9), who were treated with NPWT. Application of NPWT was associated with successful healing of wounds, leg ulcer, lymphocele and urine leak from ileal conduit.RESULTS No complications related to NPWT were reported. However, there was paucity of robust data on the effectiveness of NPWT in KT recipients; therefore, prospective studies assessing its safety and efficacy of NPWT and randomised trials comparing the effectiveness of NPWT with alternative modalities of wound management in KT recipients is recommended.CONCLUSION Negative pressure incision management system, NPWT with instillation and endoscopic vacuum-assisted closure system are in investigational stage. 展开更多
关键词 negative pressure WOUND therapy KIDNEY TRANSPLANTATION WOUND INFECTION WOUND DEHISCENCE
下载PDF
Generalized Negative Imaginary Lemma for Descriptor Systems 被引量:2
12
作者 Mohamed A. Mabrok Abhijit G. Kallapur +1 位作者 Ian R. Petersen Alexander Lanzon 《Journal of Mechanics Engineering and Automation》 2012年第1期17-21,共5页
Flexible structure dynamics with collocated force actuators and position sensors lead to negative imaginary (NI) systems. In this paper, the authors study the extension of NI theory to descriptor systems. The author... Flexible structure dynamics with collocated force actuators and position sensors lead to negative imaginary (NI) systems. In this paper, the authors study the extension of NI theory to descriptor systems. The authors derive an NI lemma for descriptor systems. This is done by using the transformation from positive real (PR) system to NI system. Then, the Weierstrass Form transformation was involved to transform A and E matrices to be in a special form. An illustrative example is presented to support the result. Negative imaginary systems, positive real systems, descriptor systems, Negative imaginary lemma. 展开更多
关键词 Positive real negative imaginary descriptor systems.
下载PDF
Hypochlorous Acid for Septic Abdominal Processes Using a Unique Negative Pressure Wound Therapy System:A Pilot Study 被引量:1
13
作者 Marc R.Matthews Asia N.Quan +7 位作者 Anushi R.Shah Carmen I.Tugulan Beshoy A.Nashed Ross F.Goldberg Paola G.Pieri Luis G.Fernandez Areta Kowal-Vern Kevin N.Foster 《Surgical Science》 2018年第11期412-421,共10页
Background: Septic open abdomens occur in trauma, burn and surgery. Currently, multiple concentrations of hypochlorous acid solutions have effectively decreased the microbiotic burden in wounds. We hypothesized that V... Background: Septic open abdomens occur in trauma, burn and surgery. Currently, multiple concentrations of hypochlorous acid solutions have effectively decreased the microbiotic burden in wounds. We hypothesized that Vashe?, a neutral hypochlorous acid solution (V-HOCL), would be safe as an intraperitoneal irrigation or washout disinfectant for septic open abdomens utilizing negative pressure wound therapy. Methods: This is a retrospective observational review of patients who required delayed abdominal closures after exploratory laparotomies. Group A (n = 8) had cyclical V-HOCL irrigation to their open abdomens combining AbtheraTM and V.A.C. Dressing System for negative pressure wound therapy with irrigation (NPWT-i) and Group B (n = 9) had intra-abdominal V-HOCL washouts. Results: Fifty percent of both groups had either septic or hemorrhagic shock on admission. Compared to Group B, Group A patients were older (median 50 vs 37 years), and had a median hospitalization of 28 vs 8 days, 4 times as many operations, more acute renal failure and co-morbidities. No statistically significant differences were detected be-tween the two treatment methods with the V-HOCL delivery and removal. Conclusion: There were no episodes of electrolyte imbalance, hypotension, hypertension, anaphylaxis, hemorrhage, visceral injury or systemic toxicity. V-HOCL with/without NPWT-i irrigation was a safe modality and tolerated well in this study. 展开更多
关键词 Abthera^(TM) Hypochlorous Acid negative Pressure Wound Therapy-Irrigation(NPWT-i) Septic Abdomen Temporary Abdominal Closure(TAC) V.A.C.VeraFlo^(TM) Vashe^(█)
下载PDF
Negative refractive index in a four-level atomic system
14
作者 张振清 刘正东 +3 位作者 赵顺才 郑军 姬艳芳 刘念 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第12期244-248,共5页
A closed four-level system in atomic vapour is proposed, which is made to possess left handedness by using the technique of quantum coherence. The density matrix method is utilized in view of the rotating-wave approxi... A closed four-level system in atomic vapour is proposed, which is made to possess left handedness by using the technique of quantum coherence. The density matrix method is utilized in view of the rotating-wave approximation and the effect of a local field in dense gas. The numerical simulation result shows that the negative permittivity and the negative permeability of the medium can be achieved simultaneously (i.e. the left handedness) in a wider frequency band under appropriate parameter conditions. Furthermore, when analysing the dispersion property of the left-handed material, we can find that the probe beam propagation can be controlled from superluminal to subluminal, or vice versa via changing the detuning of the probe field. 展开更多
关键词 quantum interference electromagnetically induction left-handed materials negative refractive index
下载PDF
Aberration-free two-thin-lens systems based on negative-index materials
15
作者 林志立 丁婕深 张朴 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第3期954-959,共6页
Since the complete correction of all five monochromatic Seidel aberrations for a singlet lens with random shape or a two-thin-lens system is unprocurable merely by using the conventional positive-index materials both ... Since the complete correction of all five monochromatic Seidel aberrations for a singlet lens with random shape or a two-thin-lens system is unprocurable merely by using the conventional positive-index materials both in theory and practice, this paper proposes that when one or both of the two lenses is/are made from negative-index materials, an imaging system composed of a pair of spherical thin lenses is possible to form a real image, in air, free from all five monochromatic Seidel aberrations. The calculated numerical solutions to the structural parameters of such lens systems possessing superior performance are provided and examples of them are illustrated for the given combinations of the two lenses' refractive indices, including an ultimately-remote imaging system. 展开更多
关键词 negative refraction negative-index materials Seidel aberrations thin lens
下载PDF
Design and evaluation of cab seat suspension system based on negative stiffness structure
16
作者 Liao Xin Zhang Ning +1 位作者 Xing Haijun Zhang Wanjie 《Journal of Southeast University(English Edition)》 EI CAS 2021年第2期153-163,共11页
To improve the vibration-isolation performance of cab seats,the optimization model of the seat suspension system of construction machinery cabs is proposed based on the negative stiffness structure.The negative stiffn... To improve the vibration-isolation performance of cab seats,the optimization model of the seat suspension system of construction machinery cabs is proposed based on the negative stiffness structure.The negative stiffness nonlinear kinetic equation is established by designing the seat negative stiffness suspension structure(NSS).Using MATLAB,the different parameters of the suspension system and their influences on the dynamic stiffness are analyzed.The ideal configuration parameter range of the suspension system is obtained.Meanwhile,the optimization model of NSS is proposed,and the vibration transmissibility characteristics are simulated and analyzed by different methods.The results show that the displacement and acceleration amplitudes of the optimized seat suspension system are evidently reduced,and the four-time power vibration dose value and root mean square calculation values in the vertical vibration direction of the seat decrease by 86%and 87%,respectively.Seat effective amplitude transmissibility(SEAT)and the vibration transmissibility ratio values also decrease.Moreover,the peak frequencies of the vibration transmitted to the driver deviate from the key frequency values,which easily cause human discomfort.Thus,the design of the seat suspension system has no effect on the health condition of the driver after being vibrated.The findings also illustrate that the NSS suspension system has good vibration-isolation performance,and the driver's ride comfort is improved. 展开更多
关键词 construction machinery negative stiffness structure seat suspension system dynamic properties ride comfort
下载PDF
Alterative wire-feed system based on arc voltage negative feedback
17
作者 傅强 薛松柏 《China Welding》 EI CAS 2012年第2期38-42,共5页
Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented const... Waveform control method was commonly adopted to reduce the spatter of CO2 arc welding and improve the weld formation. It certainly would reduce the self-regulation ability of arc due to the adoption of segmented constant current control which especially led to arc" blowout with the abrupt change oat" arc" length or downward welding. Therefore alterative wire-feed system based on arc voltage negative feedback was put forward to improve the .stability of arc" length in this paper. Double closed-loop and double fuzzy P1 regulation were adopted in this system. Fuzzy control of induced voltage was adopted in the inner-loop which improved the stability and fast response of wire-feed system. Fuzz)" control of arc" voltage negative feedback was used in the outer-loop whose output .served as the input of negative feedback regulation of inner-loop induced voltage. This method could remain arc" length and weld penetration unchan, ged on the basils of reducing spatter and improving formation and it was proved by downward welding tests. 展开更多
关键词 are voltage negative feedback CO2 are welding waveform control aherative wire-feed system
下载PDF
Negative Feedback in the Polar Ice System
18
作者 Peter Stallinga Igor Khmelinskii 《Atmospheric and Climate Sciences》 2017年第1期76-91,共16页
One of the ingredients of the anthropogenic global warming hypothesis is the existence of large positive feedback in the climate system. An example is polar ice that, once melted, turns into blacker water that will in... One of the ingredients of the anthropogenic global warming hypothesis is the existence of large positive feedback in the climate system. An example is polar ice that, once melted, turns into blacker water that will increase radiation absorption and this rein-forces the melting. This causes a run-away scenario with a point of no return. Here it is shown that the polar ice can also have negative feedback aspects, where a melting of polar ice will cause it to reappear. 展开更多
关键词 ICE ALBEDO negative FEEDBACK FRESNEL
下载PDF
A Privacy Preservation Method for Attributed Social Network Based on Negative Representation of Information
19
作者 Hao Jiang Yuerong Liao +2 位作者 Dongdong Zhao Wenjian Luo Xingyi Zhang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第7期1045-1075,共31页
Due to the presence of a large amount of personal sensitive information in social networks,privacy preservation issues in social networks have attracted the attention of many scholars.Inspired by the self-nonself disc... Due to the presence of a large amount of personal sensitive information in social networks,privacy preservation issues in social networks have attracted the attention of many scholars.Inspired by the self-nonself discrimination paradigmin the biological immune system,the negative representation of information indicates features such as simplicity and efficiency,which is very suitable for preserving social network privacy.Therefore,we suggest a method to preserve the topology privacy and node attribute privacy of attribute social networks,called AttNetNRI.Specifically,a negative survey-based method is developed to disturb the relationship between nodes in the social network so that the topology structure can be kept private.Moreover,a negative database-based method is proposed to hide node attributes,so that the privacy of node attributes can be preserved while supporting the similarity estimation between different node attributes,which is crucial to the analysis of social networks.To evaluate the performance of the AttNetNRI,empirical studies have been conducted on various attribute social networks and compared with several state-of-the-art methods tailored to preserve the privacy of social networks.The experimental results show the superiority of the developed method in preserving the privacy of attribute social networks and demonstrate the effectiveness of the topology disturbing and attribute hiding parts.The experimental results show the superiority of the developed methods in preserving the privacy of attribute social networks and demonstrate the effectiveness of the topological interference and attribute-hiding components. 展开更多
关键词 Attributed social network topology privacy node attribute privacy negative representation of information negative survey negative database
下载PDF
Negative Stiffness Mechanism on An Asymmetric Wave Energy Converter by Using A Weakly Nonlinear Potential Model
20
作者 Sunny Kumar POGULURI Dongeun KIM Yoon Hyeok BAE 《China Ocean Engineering》 SCIE EI CSCD 2024年第4期689-700,共12页
Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentia... Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions. 展开更多
关键词 asymmetric wave energy converter negative stiffness mechanism weakly nonlinear potential flow POWER
下载PDF
上一页 1 2 91 下一页 到第
使用帮助 返回顶部