45 research outputs found
Distributed cooperative control for economic operation of multiple plugāin electric vehicle parking decks
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138231/1/etep2348.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138231/2/etep2348_am.pd
Distanceāoriented hierarchical control and ecological driving strategy for HEVs
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163948/1/els2bf00154.pd
The control strength quantification analysis of outer pendulum rod for double inverted pendulum
Due to the complexity of the dynamics characteristics of an inverted pendulum, and the problem that the linearization analyze method cannot satisfy the controlling requirement, a nonlinear dynamics analyze method was proposed. Through decoupling the dynamics model of a double inverted pendulum, the outer pendulum rod motion equation was derived. And then, aiming at the control strength function of outer pendulum rod, the qualitative and quantitative relationship between spatial position of pendulum rod and the control strength of outer rod, and the quantification relationship between dynamics parameters and the control strength of outer rod were separately analyzed. And the simulation verified the correctness of the analysis
Dir-MUSIC Algorithm for DOA Estimation of Partial Discharge Based on Signal Strength represented by Antenna Gain Array Manifold
Inspection robots are widely used in the field of smart grid monitoring in
substations, and partial discharge (PD) is an important sign of the insulation
state of equipments. PD direction of arrival (DOA) algorithms using
conventional beamforming and time difference of arrival (TDOA) require
large-scale antenna arrays and high computational complexity, which make them
difficult to implement on inspection robots. To address this problem, a novel
directional multiple signal classification (Dir-MUSIC) algorithm for PD
direction finding based on signal strength is proposed, and a miniaturized
directional spiral antenna circular array is designed in this paper. First, the
Dir-MUSIC algorithm is derived based on the array manifold characteristics.
This method uses strength intensity information rather than the TDOA
information, which could reduce the computational difficulty and the
requirement of array size. Second, the effects of signal-to-noise ratio (SNR)
and array manifold error on the performance of the algorithm are discussed
through simulations in detail. Then according to the positioning requirements,
the antenna array and its arrangement are developed, optimized, and simulation
results suggested that the algorithm has reliable direction-finding performance
in the form of 6 elements. Finally, the effectiveness of the algorithm is
tested by using the designed spiral circular array in real scenarios. The
experimental results show that the PD direction-finding error is 3.39{\deg},
which can meet the need for Partial discharge DOA estimation using inspection
robots in substations.Comment: 8 pages,13 figures,24 reference
Generation of Human Epidermis-Derived Mesenchymal Stem Cell-like Pluripotent Cells and their reprogramming in mouse chimeras
Stem cells can be derived from the embryo (embryonic stem cells, ESCs), from adult tissues (adult stem cells, ASCs), and by induction of fibroblasts (induced pluripotent stem cells, iPSs). Ethical problems, immunological rejection, and difficulties in obtaining human tissues limit the use of ESCs in clinical medicine. Induced pluripotent stem cells are difficult to maintain in vitro and carry a greater risk of tumor formation. Furthermore, the complexity of maintenance and propagation is especially difficult in the clinic. Adult stem cells can be isolated from several adult tissues and present the possibility of self-transplantation for the clinical treatment of a variety of human diseases. Recently, several ASCs have been successfully isolated and cultured in vitro, including hematopoietic stem cells (HSCs) , mesenchymal stem cells (MSCs), epidermis stem cells, neural stem cells (NSCs), adipose-derived stem cells (ADSCs), islet stem cells, and germ line stem cells. Human mesenchymal stem cells originate mainly from bone marrow, cord blood, and placenta, but epidermis-derived MSCs have not yet been isolated. We isolated small spindle-shaped cells with strong proliferative potential during the culture of human epidermis cells and designed a medium to isolate and propagate these cells. They resembled MSCs morphologically and demonstrated pluripotency in vivo; thus, we defined these cells as human epidermis-derived mesenchymal stem cell-like pluripotent cells (hEMSCPCs). These hEMSCPCs present a possible new cell resource for tissue engineering and regenerative medicine
A Surface EMG System: Local Muscle Fatigue Detection
In the last 4 decades, surface electromyography (sEMG) signal processing has been applied to detect local muscle fatigue, this non-invasive approach is suitable for detecting EMG signals generated by athletes in motion. Also, EMG could directly reveal the muscleās performance like endurance and recruitment of motor units, which is hard to be obtained by other methods. With the sEMG system, we can research whether EMG signals can be used to measure muscle fatigue and how this relates to injury risk. This thesis aims to build a sensor node for sEMG to detect local muscle fatigue. An sEMG system is built for this purpose, and a physiological experiment is designed to collect sEMG signals from human muscle (Vastus Medialis) using the sEMG system. Both isometric and isotonic exercises are studied. The data analyzing method is calculating mean power spectrum frequency (MNF), median power spectrum frequency (MDF), and muscle fiber propagation velocity (MFPV) of the collected sEMG signals, because local muscle fatigue is related to MNF/MDF decrease and MFPV decrease. 5 groups of isometric exercise, wall-sit and 2 groups of isotonic exercise, cycling, are recorded. All the athletes are healthy males, around 25. The data analyzing result shows that MNF/MDF decrease is related to muscle fatigue, and MFPV changes similarly with MNF/MDF
A Model for Urban Environment and Resource Planning Based on Green GDP Accounting System
The urban environment and resources are currently on course that is unsustainable in the long run due to excessive human pursuit of economic goals. Thus, it is very important to develop a model to analyse the relationship between urban economic development and environmental resource protection during the process of rapid urbanisation. This paper proposed a model to identify the key factors in urban environment and resource regulation based on a green GDP accounting system, which consisted of four parts: economy, society, resource, and environment. In this model, the analytic hierarchy process (AHP) method and a modified Pearl curve model were combined to allow for dynamic evaluation, with higher green GDP value as the planning target. The model was applied to the environmental and resource planning problem of Wuyishan City, and the results showed that energy use was a key factor that influenced the urban environment and resource development. Biodiversity and air quality were the most sensitive factors that influenced the value of green GDP in the city. According to the analysis, the urban environment and resource planning could be improved for promoting sustainable development in Wuyishan City
A Novel Wide-Band Directional MUSIC Algorithm Using the Strength Proportion
The directional multiple signal classification (Dir-MUSIC) algorithm based on the antenna gain array manifold has been proposed to find the direction of the partial discharge (PD) source in substations. However, PD signals are wideband signals and the antenna gain pattern functions are always different at different frequencies; therefore, the accuracy can be improved using a wideband Dir-MUSIC algorithm. In this paper, wideband Dir-MUSIC algorithms are discussed and a novel wideband Dir-MUSIC algorithm using the strength proportion (DirSP) is proposed. This algorithm estimates a focusing PD signal at a certain frequency using the strength proportion among different directions, and then the Dir-MUSIC algorithm can process the focusing PD signal at this frequency. In simulations, when the antenna gain functions among different frequency bins are quite different, the Dir-MUSIC algorithm loses accuracy; meanwhile, DirDP performs very well. In the experiments, we deal with six sets of samples, and the mean error and standard deviation are both smaller than 4Ā° better than other methods
Identifying distributions of urban ecosystem health based on Latin-hypercube sampling and multi-criteria decision analysis framework
In this study, a hybrid approach was established to identify future heterogeneity of urban ecosystem health (UEH) transferred by variations of land-use, socio-economic development, and ecological function in lower scales of cities (i.e., districts), incorporating uncertainty analysis into a multi-criteria decision assessment framework. In consideration of multiple driving factors of UEH scores, the contribution of the main indicators to UEH scores was identified by geographical detector model. To verify effectiveness of the approach, a case study was applied in Dongguan City of China. The results indicated that UEH scores of Dongguan didnāt greatly change during 2010ā2020. Conversely, the scores would increase from 2023 to 2030, influenced by socio-economic development and ecological function under the district scale. Concurrently, the heterogeneity of urban ecosystem health ranks (UEHRs) in 32 districts occurred during 2010ā2020, further influencing UEH scores of Dongguan. Owing to inconsistent of land-use, ecological function, and socio-economic development of districts, the heterogeneity of UEHRs was intensified in 2025ā2030. From 2010 to 2020, the spatial variations of UEH scores in Dongguan City depended on the synergy of land-use intensity and economic growth. The joint influence from economic development, energy consumption and land-use patterns would contribute greatly to the variations of UEH scores in Dongguan City from 2023 to 2030. Thus, heterogeneity of UEHRs under district scale as well as promotion for sustainable economic development should be paid attention to by decision-makers, to identify internal characteristics in urban ecosystems
Thermoplastic Azobenzene Polyurethanes with Both Efficient Photomediated Migration and Excellent Mechanical Strength
Azobenzene
polymers with efficient photomediated migration
are
highly desired because of their potential application in sensors,
actuators, and information storage devices. Various methods have been
developed to improve photosensitivity of azobenzene polymers; however,
performances of the reported polymers so far are still less than satisfactory.
While azobenzene polymers of high glass transition temperature (Tg) or melting temperature (Tm) are usually of practical use, photomigration in high Tg (or Tm) azobenzene
polymers is difficult because polymer chains are frozen at low temperature.
Here, we report the preparation of thermoplastic azobenzene polyurethanes
(azo TPUs) with both efficient photomediated migration and excellent
mechanical performances. These TPUs are in the phase-separated state
with hard microdomains of high Tm embedded
in a soft matrix of low Tg. Because of
their high Tm, these azo TPUs are mechanically
strong with maximum stress exceeding 8 MPa. However, as a result of
the two-phase design with the majority of materials being a soft component
with low Tg, these azo TPUs also show
efficient photomigration of micrometers under UV irradiation (125
mW/cm2, 160 s) despite their high Tm. At higher amplitude of UV light (>500 mW/cm2)
and in the presence of a photothermal effect, rare macroscopic mass
transportation of centimeter was observed. These azo TPUs may find
application in actuators, optical information storage devices, or
as optical healable materials