Index Distribution Research Articles

Estimating the Generalizations of Process Capability Index Cpmk$C_{pmk}$ in the Presence of Outliers

ABSTRACTProcess capability indices (PCIs) play a fundamental role in assessing and quantifying the capability of manufacturing processes to meet customer specifications. To date, the majority of PCIs that are now in use have been examined through the use of novel generalizations of PCIs with symmetric tolerances to check the performance of an industrial manufacturing process. In this paper, we proposed new estimations of some indices with asymmetric tolerances in the presence of outliers. New robust and parametric estimators of some PCIs are introduced to estimate and compare these indices for each normal distribution with the presence of different outliers. Meanwhile, this paper discusses how well the proposed method can be used for non‐normal data. For illustration purpose, the application example is presented.

Non-thermal emission in galaxy groups at extremely low frequency: The case of A1213

Galaxy clusters and groups are the last link in the chain of hierarchical structure formation. Their environments can be significantly affected by outbursts from active galactic nuclei (AGN), especially in groups where the medium density is lower and the gravitational potential is shallower. Thus, interaction between AGN and group weather can greatly affect their evolution. We investigate the non-thermal radio emission in Abell 1213, a galaxy group that is part of a larger sample of sim 50 systems (X-GAP) recently explored in XMM-Newton observations. We exploited proprietary LOFAR 54 MHz and uGMRT 380 MHz observations, complementing them with 144 MHz LOFAR survey and XMM-Newton archival data. A1213 hosts a bright AGN associated with one of the central members, 4C\,29.41, which was previously optically identified as a dumb-bell galaxy. Observations at 144 MHz at a resolution of 0.3$''$ have allowed us to resolve the central radio galaxy. From this source, a $ 500$ kpc-long tail extends in the north-east direction. Our analysis suggests that the tail likely originated from a past outburst of 4C\,29.41 and its current state might be the result of the interaction with the surrounding environment. The plateau of the spectral index distribution in the easternmost part of the tail suggests mild particle re-acceleration, which could have re-energised seed electrons from the past activity of the AGN. While we do observe a spatial and physical correlation of the extended, central emission with the thermal plasma (which might hint at a mini-halo), the current evidence cannot prove this conclusively. A1213 is only the first group among the X-GAP sample that we have been able to investigate via low-frequency radio observations. Its complex environment once again demonstrates the significant impact that the interplay between thermal and non-thermal processes can exert on galaxy groups.

Refractive Index Morphology Imaging Microscope System Utilizing Polarization Multiplexing for Label-Free Single Living Cells.

Detections of internal substances and morphologies for label-free living cells are crucial for revealing malignant diseases. With the phase serving as a coupling of refractive index (RI) (marker for substances) and thickness (morphology), existing decoupling methods mainly rely on complex integrated systems or extensive optical field information. Developing simple and rapid decoupling methods remains a challenge. This study introduces a refractive index morphology imaging microscope (RIMIM) system utilizing polarization multiplexing for label-free single living cells. By simultaneous degree of circular polarization (DOCP) imaging and noninterferometric quantitative phase imaging (QPI), the intracellular refractive index distribution (IRID) and morphology can be decoupled. The optical thickness calculated from the phase is input into the circular depolarization decay model (CDDM) of degree of circular polarization to retrieve IRID. Subsequently, the thickness can be decoupled from phase result using retrieved IRID. Experiments conducted on mouse forestomach carcinoma (MFC) cells and human kidney-2 cells (HK-2) demonstrated the RIMIM system's ability to retrieve IRID and decouple fine morphology. Additionally, the RIMIM system effectively detected membrane damage and changes in erastin-induced ferroptotic HK-2 cells, with average and root-mean-square of surface folds 65.5% and 70.0% higher than those of normal HK-2 cells. Overall, the RIMIM system provides a simple and rapid method for decoupling RI and fine morphology, showing great potential for label-free live cells' cytopathology detection.

Future Population Aging in Bangladesh: Economic and Social Aspects

Recently, Bangladesh has entered into a lower-middle-income country and faces various challenges like other developed countries of the world regarding its population. Eventually, aging will become a challenge for its progressive economy and society. This paper aims to identify the future time periods in which the majority of the indices confirm Bangladesh as an aging country. This study estimates various demographic indices to reveal the age structural transition of Bangladesh's population for 2011-2061. Furthermore, it has computed general distribution indices, the aging index, the Billeter index as reproductive indices, and several economic and support dependency ratios. The trend line of the coefficients of inflow, outflow, and exchange of the productive population has been drawn in order to visualize the future workforce. It has been observed that Bangladesh will be an aging country between 2030 and 2035, taking into account major traditional measures of population aging. In this sense, it is a novel finding for policy implications to overcome the upcoming challenges of the inevitable population aging in Bangladesh. To deal with the implications and drivers of population ageing several steps are required to consider by the government and private institutions. International Journal of Statistical Sciences, Vol. 24(2), November, 2024, pp 109-124

New Insight into Industrial Lignin Intermolecular Force Heterogeneity Mitigation: Monodispersed Lignin Colloidal Sphere Synthesis and Full Biomass Photonic Material Preparation.

Industrial lignin is an underutilized resource from the pulping industry due to its high heterogeneity. The transformation of industrial lignin into monodispersed lignin colloidal spheres (LCSs) for the preparation of advanced biomass photonic materials is particularly appealing, because of their unique biocompatibility. However, the LCSs synthesized from industrial lignin generally show a wide size distribution and thus limit this specific application. To address the issue, selective functionalization was carried out to convert phenolic and aliphatic -OH groups into ester groups, decreasing the LCS size distribution to a monodispersing degree. Simulation analysis revealed that the functionalization had narrowed the difference of C-O linkage electron cloud distribution and led to a lignin polarity decrease. Additionally, atomic force microscopy (AFM) quantification of lignin proved a force distribution index (FDI) decrease from 0.38 to 0.11, which was consistent with the LCS polymer dispersity index (PDI) decrease from 0.182 to 0.05. The photonic materials can be readily prepared from monodispersed LCSs with the color precisely adjusted by controlling LCS particle sizes.

Influence investigation of morphological and distributional properties of surficial aggregates on skid resistance of asphalt pavement

Skid resistance of the asphalt pavement is greatly influenced by the morphology and spatial distribution of surficial aggregates on the pavement. To clarify the correlation between them, this study accurately detects and segments the mesh of aggregates in the pavement model reconstructed by the laser scanner. Subsequently, three morphological indices (the peak height, cross-section form, and root-mean-square gradient of an aggregate) and two distributional indices (the aggregate spacing, and aggregate distribution dispersity) were calculated. Simultaneously, British pendulum number was also measured to represent the skid resistance of the pavement. At last, the correlation between the British pendulum number and five indices of surficial aggregates of the pavement was obtained using the grey relation method. Especially, the mesh segmentation algorithm developed was enhanced in splitting adhesive mesh of adjacent aggregates and restoring incorrectly splitted mesh of aggregates to improve the accuracy and robustness of the algorithm. Six regions on the surface of two rut specimens under SMA-16 and GAC-16 gradations were selected to analyze the correlation between British pendulum number and the five indices. Results indicate that the cross-section form influences the skid resistance of the pavement most, followed by the aggregate spacing, aggregate distribution dispersity, aggregate peak height, and aggregate RMS gradient. This facilitates the potential directions to improve the skid resistance by optimizing the highly relevant indices in future.

Design of a tunable microlens based on hybrid single-wall carbon nanotube and liquid crystal

: Tunable liquid crystal (LC) lenses have garnered significant interest in recent years for their lightweight, cost-effectiveness, and versatility in applications like augmented reality, ophthalmic devices, and astronomy. Despite numerous proposed structures to enhance LC lens performance, achieving a minimal focal length while preserving image quality and balancing cost and complexity remains a daunting challenge. Adaptive microlenses encounter these obstacles due to physical constraints and diffraction effects. One promising solution lies in using adaptive LC-carbon nanotubes (CNTs) lenses. By adjusting external stimuli like electric or magnetic fields, it is possible to modify the refractive index distribution of the LC medium, thus changing the focal length of the microlens. When paired with CNTs, the LC molecules' orientation and control of focal length can be even more precise. Our research findings suggest that to achieve the shortest focal length in a microlens with a thickness of 22.5 μm, it is recommended that the diameter of the CNT should not exceed 10 nm, and the height of CNT should fall within the range of 10 to 20 μm considering the presence of screening effect. Conversely, for a microlens with low full width at half maximum (FWHM), narrower light spot, it is advisable to use CNT with a diameter larger than 100 nm and a height greater than 13 μm. Additionally, for a microlens with an efficient Fresnel number in the range of 1 to 10, the microlens should have CNT with widths from 100 to 200 nm. Therefore, based on the importance of each factor (focal length, FWHM, and Fresnel number), the dimensions of the carbon nanotube can be selected to suit the desired application.

Langmuir solitons in plasma with κ-deformed Kaniadakis distributed electrons in the kinetic regime

The dynamics of Langmuir solitons in plasma with κ-deformed Kaniadakis distributed electrons is studied. First, a Zakharov-type equation describing the evolution of the fields of Langmuir and ion-acoustic wave is derived in a kinetic regime. Then, in the one-dimensional case, the Zakharov-type equation is reduced to the well-known nonlinear Schrödinger equation that is applied to investigate the characteristics of modulated Langmuir wave packets. It is shown that there are two types of solitons, one is bright soliton in the subsonic regime and the other is dark soliton in the supersonic regime. It also found that when the amplitudes of both types of solitons are fixed, the width of bright soliton increases, while the width of dark soliton decreases, with increased distribution index κ. The present work may serve as a preliminary investigation into the nonlinearity of the κ-deformed Kaniadakis distributed plasma system.

Analysis of Andisol Soil Quality Index in Scallion (Allium fistulosum L.) Agricultural Land in Tosari District, Pasuruan Regency

Soil quality assessment can be done by monitoring the dynamic conditions of various indicators that influence it. Measuring these indicators produces a soil quality index (IKT), which is a tool to evaluate the impact of land management practices (Mas'udi et al., 2021). This research aims to determine the distribution of the soil quality index on shallot (Allium fistulosum L) agricultural land in Tosari sub-district, Pasuruan district, East Java. The research was carried out in Tosari sub-district, Pasuruan district at an altitude of 1700 meters above sea level. In September 2023 – January 2024. This research uses a purposive sampling method for taking soil samples. Next, it was analyzed in the laboratory for texture, volume weight, porosity, C-organic, pH, P-available, K-exchangeable and the rooting depth was measured. The soil quality index is calculated using the criteria of Mausbach and Seybold (1998), which can be adjusted to field conditions using the Minimum Data Set (MDS). Based on the research results, it shows that there are differences in the Soil Quality Index on Onion Leaf land in several villages in Tosari sub-district. Leek fields in Tosari sub-district have two criteria, namely medium and good criteria. Tosari Village, Ngawidono Village, Mororejo Village and Kandangan Village are classified as Good (B) while Podokoyo Village is classified as Medium (S).

Seismic Response Analysis of a Vibrating Stirred Steel Fiber Concrete Frame Structure Based on Probability Density Evolution

In this paper, an experimental study of steel fiber concrete using vibration mixing technology and the probability density evolution theory is applied to establish a nonlinear stochastic seismic response model for multistory concrete frame structures considering the randomness of structural parameters. The random evolution characteristics of the structural response are studied and analyzed, and a reliability analysis method for concrete frame structures based on PDEM theory is proposed. The equations are solved by the finite difference method in the TVD format, and the probability distribution of the deformation index of the concrete frame structure is obtained by summation, where the reliability is given according to the limit value of the index. The results confirm that the PDEM theory can accurately assess the functional reliability of the structure, and it is also found that the randomness of the structural parameters has a significant effect on its nonlinear dynamic response law, and that consideration of the randomness of the structural parameters at the early stage of the design can be of great help to the seismic resistance of the structure. This study not only provides a scientific basis for the optimization of the performance of steel fiber concrete but also provides a new perspective and tool for the analysis of probability density evolution in the field of structural earthquake engineering.

Analyzing AZ-non-Maxwellian distributions in Earth’s magnetosphere: MMS observations

A study of velocity distribution function in Earth’s magnetosphere is conducted using high-resolution measurements from the Magnetospheric Multiscale Spacecraft (MMS). The analysis focuses on the AZ-non-Maxwellian distribution that is a complex velocity-space structure, exhibiting a power-law distribution of moments. By imposing constraints on the spectral indices of the AZ-velocity distribution, the most suitable distribution for modeling Earth’s magnetosphere is determined. The combined use of MMS data and analysis of velocity distribution provides new insights into the behavior of plasma particles and the velocity space structures responsible for energy dissipation in plasmas. Understanding particle distribution, behavior, and the influence of cold ions in Earth’s magnetosphere is crucial for advancing our knowledge of plasma physics and has practical implications for space weather and magnetospheric dynamics. Addressing the remaining uncertainties and challenges in measurements, analysis of non-Maxwellian distribution of ions is essential for a comprehensive understanding of space plasma environments.

Differential phase contrast intensity diffraction tomography.

Intensity diffraction tomography (IDT) is a label-free computational microscopy technique that infers 3D refractive index (RI) and absorption distributions of objects from intensity-only measurements. Nevertheless, the inherent coherent image formation model requires sequential intensity measurements under various plane wave illuminations, resulting in time-consuming data acquisition and low imaging speed. In this Letter, we propose differential phase contrast intensity diffraction tomography (DPC-IDT), which leverages partially coherent illumination to extend the accessible spectrum range, thereby achieving high-speed, motion-free 3D tomographic microscopy. DPC-IDT integrates DPC illumination within the IDT framework, allowing 3D RI tomogram reconstruction from only four intensity images under matched asymmetric annular illumination. The effectiveness of DPC-IDT is experimentally validated by RI measurements of standard microspheres. We also demonstrate dynamic 3D imaging results of living PLC cells at a 25 Hz volume rate, highlighting its potential for high-speed biological imaging of unstained samples.

Accumulation of metals and metalloids in soil cover, road dust, and their PM10 fraction in Ulan-Ude: Spatial variation and source apportionment

Coal-fired thermal power plants remain one of the primary sources of electricity generation in the Asian part of Russia. However, coal combustion leads to severe environmental pollution. This study attempts to assess this impact in a large city in Eastern Siberia, Ulan-Ude, the capital of Buryatia, where coal is widely used in thermal power plants and for stove heating. The accumulation of trace metals (MMs) in the upper soil horizons, road dust, and their fine PM10 fraction was evaluated. The coal, ash, soil and road dust samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS/AES) to determine concentrations of As, Bi, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, Sr, V, W, and Zn. The coal was enriched only in Sr compared to world coals, while the ash was depleted in all these MMs. Concentrations of all MMs were higher than the local natural soil background values, with priority pollutants in Ulan-Ude's soils identified as Cu, Pb, Sb, Cd, Zn, and W. For the first time, the primary sources of MMs were quantitatively assessed using the PMF receptor model. It was established that most MMs (As, Ni, Cr, Sr, V, Co, Bi) originated from mixed sources, including natural sources and emissions from coal combustion. Its contribution accounted for 32.6 % for the bulk soils and 25.4 % for the PM10 fraction. The contribution of exhaust and non-exhaust emissions was estimated as 19.2 % and 22.4 % for bulk soils and the PM10 fraction, respectively. The spatial distribution of the Total Pollution Index (TPI) for soils indicated that the pollution degree was highest in private residential areas (mean TPI = 24), suggesting an influence of coal combustion conditions (including temperature) on contamination levels. The PM10 fraction of soil was most polluted in the railway transport zone (mean TPI = 46). Approximately 8 % of Ulan-Ude's territory displayed maximum, extremely hazardous levels of pollution in soils and their PM10 fraction, posing a risk to human health. Road dust was enriched in Sr, Sb and Pb compared to the continental upper crust values. Bulk road dust exhibited a low level of pollution, while the Total Pollution Index for its PM10 fraction reached an extremely hazardous level (TPI > 128). The highest pollution levels in road dust and its PM10 fraction were observed on main roads. In large industrial cities, pollution from coal combustion occurs alongside other significant sources, including vehicular emissions, contributing to the diversity of total pollutant emissions.

Measurement of plasma characteristic parameters of copper foil explosion using interferometry

The accurate testing of plasma temperature and electron density and shock wave pressure during an electroburst in a copper foil transducer is critical for the characterization of the detonation performance of its elements. In this paper, the sequence of interferograms during the detonation of a copper foil transducer is captured at a frame rate of 3×106fps in conjunction with Mach–Zehnder interferometry and high-speed photography, and the results clearly demonstrate the propagation of the shock wave wavefront and plasma. The phase differences disturbed by plasma are extracted using the Fourier transform method, and the refractive index distributions are reconstructed with the Abel algorithm. Subsequently, based on the refractive index models of the shock wave and plasma, the shock wave pressure and plasma temperature and electron density are partitioned and reconstructed. Results show that the maximum shock wave pressure in the detonation of the copper foil transducer element is 1.297 atm, the maximum plasma temperature is 16,280 K, and the maximum plasma electron density is 2.134×1017cm−3. This study provides a theoretical and technical foundation for the detonation performance testing of pyrotechnic energy-conversion components.

The joint distribution of years lived in good and poor health

BackgroundIncidence-based multistate models of population health are commonly applied to calculate state expectancies, such as a healthy life expectancy (HLE), or unhealthy life expectancy (UHE). These models also allow the computation of other summary indices, such as the distributions of healthy or unhealthy lifespans.ObjectiveWe aim to show how a multistate health model implies a multistate death distribution, giving joint information on years lived in good and poor health. We also propose three aggregate indices of joint health and mortality inequality.MethodsWe propose a double-accounting approach to increment-decrement life table methods to intuitively derive a multistate health distribution over age and cumulative duration spent in each state. We then define a variety of summary lifespan inequality indices based on different distance metrics, namely Euclidean, Chebyshev, and Manhattan distances.ResultsWe apply the method to multistate transition probabilities between health states based on the activities of daily living index for Italian women from the Survey of Health, Ageing and Retirement in Europe in 2015-2017. We demonstrate the added value of accounting for joint years lived in health states in multistate models for our understanding of the period health and mortality conditions from the perspective of health-specific lifespans of individuals.ConclusionsMultivariate state distributions and summary indices derived from them give a holistic representation of population health inequality. We offer selected summary indices of the multivariate distribution with different demographic interpretations from the measures derived from univariate distributions. Although more theoretical and methodological work is required to motivate a single comprehensive population health inequality index, this direction is a promising path for a better understanding of population health dynamics and relationships between univariate statistics.

Immunological Profiles, Oxidative Stress Biomarkers and Plasma Cholinesterase Activities in Patients with Immune-Mediated Inflammatory Diseases Treated in a Clinic in Duhok, Iraq

Abstract Aim The purpose of the present study was to measure the levels of selected plasma biochemical variables among cases of immune-mediated inflammatory diseases (IMIDs), other than rheumatoid arthritis, treated in a clinic in the city of Duhok, Iraq, since such information is scarce in the region. Materials and Methods A case-control study on IMIDs patients treated in a clinic in Duhok, Iraq, was performed from February 2022 to June 2023. A total of 29 patients of both genders with IMIDs and 61 healthy controls were recruited at the Duhok Center for Rheumatic Diseases and Medical Rehabilitation, Duhok, Iraq. The laboratory tests conducted on plasma samples from IMIDs patients and healthy controls included measurements of interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, malondialdehyde (MDA), total antioxidant status (TAS) and cholinesterase (ChE) activity. Results No significant differences were found in gender distribution, age, and body mass index between the IMIDs patients and healthy controls. The majority of patients (69%) received conventional therapy combined with biologic agents, whereas the remaining patients (31%) received only conventional medications. The IMIDs identified among the 29 patients were Behcet’s disease (27.6%), ankylosing spondylitis (24.1%), inflammatory bowel diseases (24.1%), psoriatic arthritis (10.3%), systemic lupus erythematosus (6.9%) and psoriasis (6.9%). Conventional therapy used was mostly azathioprine (44.8%) and methotrexate (17.2%), whereas biological therapy included mostly etanercept (27.6%) and adalimumab (24.1%). The values of CRP, IL-6 and TNF-Į among the IMIDs patients were not significantly different from those of the controls. The oxidative stress biomarker MDA was elevated in IMID patients (2.93 ± 1.106 —mol/L vs. 2.52 ± 0.478) at a p value of 0.064 (though not significant). The TAS level (1.21 ± 0.422 mmol Trolox Equiv./L vs. 1.00 ± 0.338, p = 0.022) and plasma ChE activity (1.18 ± 0.50 ¨ pH/20 min vs. 0.83 ± 0.30, p = 0.001) were significantly higher in IMIDs patients compared to controls. Conclusions The data suggest that oxidative stress and changes in plasma ChE activity might be a part of the pathophysiological alterations among IMIDs patients. Therapeutic drug monitoring and its clinical outcome as well as response of IMIDs patients to anti-ChE agents are worth of further in depth exploration and pursuing. They are essential for better diagnosis, treatment, and management of IMIDs.

Effect of High-Stress Levels on the Shear Behavior of Geosynthetic-Reinforced Marine Coral Sands

As an important construction material, the mechanical and deformation properties of marine coral sand determine the safety and stability of related island and coastal engineering construction. The porous and easily broken characteristics of coral sand often make it difficult to meet engineering construction needs. In particular, coral sand undergoes a large amount of particle breakage under high-stress conditions, which in turn negatively affects its mechanical and deformation properties. In this study, the macro- and micro-mechanical behavior of geosynthetic-reinforced coral sand under high confining pressure was investigated and compared with unreinforced cases using the three-dimensional discrete element method (DEM), which was verified by indoor triaxial tests. The results showed that the stress–strain responses of unreinforced and reinforced coral sand under high confining pressure showed completely different trends, i.e., the hardening tendency shown in the reinforced case. Geosynthetic reinforcement can significantly inhibit the stress–strain softening and bulging deformation of coral sand under high confining pressure, thus improving the shear mechanical performance of the reinforced sample. At the microscopic scale, high confining pressure and reinforcement affected the contact force distribution pattern and stress level between particles, determining the macroscopic mechanical and deformation performance. In addition, the breakage of particles under high confining pressure was mainly affected by shear strain and reinforcement. The particle fragment distribution, particle gradation, and relative breakage index exhibited different trends at different confining pressure levels. These breakage characteristics were closely related to the deformation and stress levels of unreinforced and reinforced samples.

Associations Between Deficit Accumulation Frailty and Baseline Markers of Lifestyle in the US POINTER Trial.

Multidomain lifestyle interventions may have the potential to slow biological aging as captured by deficit accumulation frailty indices. We describe the distribution and composition of the 49-component frailty index (FI) developed by the U.S. POINTER clinical trial team of investigators and assess its cross-sectional associations with sociodemographic factors and markers chosen to be representative of behaviors targeted by the trial's multidomain interventions. We draw baseline data from the 2111 volunteers enrolled in U.S. POINTER who were ages 60-79 years and at increased risk for cognitive decline. Frailty components were grouped into nine domains. Associations that FI scores and their domains had with behavioral markers were described with correlations and canonical correlation. The 25th, 50th, and 75th percentiles of the frailty index score distribution were 0.153, 0.189, and 0.235. Higher frailty scores tended to occur among individuals who were older, male, and living in areas of greater deprivation (all p<0.001). They were also associated with poorer self-reported diet, less physical activity, and higher Framingham risk scores (all p<0.001). Associations were diffusely distributed among the frailty component domains, indicating that no individual domain was dominating associations. The U.S. POINTER deficit accumulation frailty index had expected relationships with sociodemographic factors and sensitivity to the behaviors targeted by the trial's interventions. Our analysis supports its use as a secondary outcome to assess whether the multidomain interventions differentially impact an established marker of biological aging.

Neuroimaging Insights into Brain Mechanisms of Early-onset Restrictive Eating Disorders.

Early-onset restrictive eating disorders (rEO-ED) encompass a heterogeneous group of conditions, including early-onset anorexia nervosa (EO-AN) and avoidant restrictive food intake disorders (ARFID). Almost nothing is known about the consequences of rEO-ED on brain development. We performed the largest comparison of MRI-derived brain features in children and early adolescents (<13 years) with EO-AN (n=124), ARFID (n=50), and typically developing individuals (TD, n=112). Despite similar body mass index (BMI) distributions, EO-AN and ARFID showed divergent structural patterns, suggesting independent brain mechanisms. Half the regional brain measures were correlated with BMI in EO-AN and none in ARFID, indicating a partial mediation of EO-AN signal by BMI. EO-AN was associated with a widespread pattern of thinner cortex, while underweight ARFID patients exhibited smaller surface area and subcortical volumes than TD. Future studies will be required to partition the contribution of low BMI vs. ED mechanisms in neurodevelopmental disorders.

Deterministic Trajectory Design and Attitude Maneuvers of Gradient-Index Solar Sail in Interplanetary Transfers

A refractive sail is a special type of solar sail concept, whose membrane exposed to the Sun’s rays is covered with an advanced engineered film made of micro-prisms. Unlike the well-known reflective solar sail, an ideally flat refractive sail is able to generate a nonzero thrust component along the sail’s nominal plane even when the Sun’s rays strike that plane perpendicularly, that is, when the solar sail attitude is Sun-facing. This particular property of the refractive sail allows heliocentric orbital transfers between orbits with different values of the semilatus rectum while maintaining a Sun-facing attitude throughout the duration of the flight. In this case, the sail control is achieved by rotating the structure around the Sun–spacecraft line, thus reducing the size of the control vector to a single (scalar) parameter. A gradient-index solar sail (GIS) is a special type of refractive sail, in which the membrane film design is optimized though a transformation optics-based method. In this case, the membrane film is designed to achieve a desired refractive index distribution with the aid of a waveguide array to increase the sail efficiency. This paper analyzes the optimal transfer performance of a GIS with a Sun-facing attitude (SFGIS) in a series of typical heliocentric mission scenarios. In addition, this paper studies the attitude control of the Sun-facing GIS using a simplified mathematical model, in order to investigate the effective ability of the solar sail to follow the (optimal) variation law of the rotation angle around the radial direction.