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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
文摘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.
文摘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.
文摘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.
基金Supported by National Natural Science Foundation of China(Grant No.51575199)
文摘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.
文摘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.
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China(11472044,11221202,11632003,11521062)the 111 Project(B160030)
文摘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.
基金This study was supported jointly by the National Natural Science Foundation (49070172)of China and the Foundation for Development of Science and Technology in Geology of the Ministry of Geology and Mineral Resources of China.
文摘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.
文摘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.
文摘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.
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60768001 and 10464002)
文摘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.
基金Project partially supported by the National Basic Research Program of China(Grant No2004CB719802)an additional support from the Science and Technology Department of Zhejiang Province,China
文摘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.
基金The National Natural Science Foundation of China(No.11902207,No.52072072)the Natural Science Foundation of Hebei Province(A2020210018)Higher Education Teaching Research Project(No.Y2020-15).
文摘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.
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China(Nos.62006001,62372001)the Natural Science Foundation of Chongqing City(Grant No.CSTC2021JCYJ-MSXMX0002).
文摘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.
基金financially supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Grant No.2022R1I1A1A01069442)the 2024 Hongik University Research Fund。
文摘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.