Relative Depth Research Articles

Frequency selective low-loss transmission in negative curvature hollow-core fibers

A new low-loss negative curvature fiber design, named as the pole-anchored nested tubular negative curvature fiber, which exhibits frequency selective capabilities in the near-infrared region is proposed. This unique approach involves the addition of nested tubular elements anchored by vertical poles, which serve as an in-fiber resonator. The resulting frequency selective resonant loss dips exhibit high finesse and relative loss modulation depth. The concept of frequency selectivity in negative curvature fibers introduces unique possibilities for future applications of hollow-core structures.

Psychoacoustic and electroencephalographic responses to changes in amplitude modulation depth and frequency in relation to speech recognition in cochlear implantees

Temporal envelope modulations (TEMs) are one of the most important features that cochlear implant (CI) users rely on to understand speech. Electroencephalographic assessment of TEM encoding could help clinicians to predict speech recognition more objectively, even in patients unable to provide active feedback. The acoustic change complex (ACC) and the auditory steady-state response (ASSR) evoked by low-frequency amplitude-modulated pulse trains can be used to assess TEM encoding with electrical stimulation of individual CI electrodes. In this study, we focused on amplitude modulation detection (AMD) and amplitude modulation frequency discrimination (AMFD) with stimulation of a basal versus an apical electrode. In twelve adult CI users, we (a) assessed behavioral AMFD thresholds and (b) recorded cortical auditory evoked potentials (CAEPs), AMD-ACC, AMFD-ACC, and ASSR in a combined 3-stimulus paradigm. We found that the electrophysiological responses were significantly higher for apical than for basal stimulation. Peak amplitudes of AMFD-ACC were small and (therefore) did not correlate with speech-in-noise recognition. We found significant correlations between speech-in-noise recognition and (a) behavioral AMFD thresholds and (b) AMD-ACC peak amplitudes. AMD and AMFD hold potential to develop a clinically applicable tool for assessing TEM encoding to predict speech recognition in CI users.

Exhumation of the Qilian Shan and Miocene activity of the Haiyuan fault: insights from apatite (U–Th)/He thermochronology in the Laolongwan basin, northeastern Tibetan Plateau

The Tibetan Plateau, which is deformed by the collision between the Indian and Eurasian plates, is a natural laboratory in which to study intracontinental deformation related to northeastward growth of the plateau. However, how and when the Tibetan Plateau propagated to its present-day margins remain unclear. The Qilian Shan and Haiyuan fault, which serve as the topographic and geological boundaries of the high plateau, are key to revealing the uplift and expansion of the Tibetan Plateau. Here, we present detrital apatite (U–Th)/He and reverse modelling results from the Laolongwan basin, which is interpreted as a pull-apart basin controlled by activity of the Haiyuan fault in the east portion of the Qilian Shan region. Our results reveal three-stage tectono-thermal evolution of Qilian Shan: (1) Late Jurassic to Cretaceous rapid exhumation; (2) Late Cretaceous to middle Miocene tectonic quiescence period; and (3) exhumation after the middle Miocene. We suggest that the Jurassic to Cretaceous rapid exhumation might be related to the convergence of the Lhasa block with the Eurasian plate or regional extension during the Mesozoic closure of the Meso-Tethys, and the mid-Miocene accelerated exhumation was driven by Haiyuan fault activation related to the growth of the Tibetan Plateau to its northeastern margin. Supplementary material: Time–temperature paths of (U–Th)/He thermal history models (Fig. S1) and AHe age–depth relationship (Fig. S2) are available at https://doi.org/10.6084/m9.figshare.c.7018149 Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change

Laboratory investigation on pore pressures inside a rubble mound breakwater in depth-limited waters

The present paper reports the analysis of pore pressure measurements acquired inside a small-scale conventional breakwater during an experimental campaign performed at the EUMER laboratory of the University of Salento (Lecce, Italy). The new data are used to investigate the effects of depth-limited water conditions on the wave-induced pressures in a porous structure in front of a 1V:30H foreshore. Specifically, the paper addresses and discusses the impact of the relative depth on three aspects: the frequency response of pore water pressure in the structure, the energy dissipation through the cover layers and the pressure attenuation inside the breakwater core. Additionally, the paper includes a comparison between the experimental results and the empirical models actually available in literature, able to predict the reference pressure at the armour/filter layers interface and the pressure damping inside porous structures. Results firstly show that shallow water conditions amplified the influence of wave long components on breakwater response to wave action, inducing a pressure attenuation inside the structure of about 80%−90%, mostly between the armour and the filter layers and highly dependent on the wave period. Instead, the comparison with the empirical formulae shows that the predictive models considered in the present work generally underpredict the damping coefficient, especially in intermediate/shallow water conditions, demonstrating that the relative depth has a high influence on both the reference pressure and the damping coefficient.

Multi-stage micrite diagenesis in the late Jurassic of the Eastern Paris Basin: petrophysical and mechanical properties for engineering purposes

Abstract The Calcaires du Barrois Formation is a succession of dominantly micritic limestone of Kimmeridgian to Tithonian age, outcropping in the eastern part of the Paris Basin. This is an active karstic aquifer of interest to Andra (French National Agency for Radioactive Waste Management), who are studying the feasibility of a deep geological repository of radioactive waste in an underground research laboratory located approximately 450 m below the surface. Surface installations of the Industrial Centre for Geological Disposal project are planned in the upstream recharge zone of the aquifer. It is of primary interest to characterize the Calcaires du Barrois Formation to provide guidelines for the planning and sizing of these facilities, to minimize the impact on the aquifer system. An integrated study was designed for this purpose, linking petrography (thin section and scanning electron microscopy), carbon and oxygen stable isotope geochemistry, X-ray diffraction, petrophysics and geomechanics. It is based on the analysis of three key cored wells penetrating the formation at different relative depths. The Calcaires du Barrois have undergone several stages of diagenesis that have defined the current properties. Unconformities associated with the Jurassic–Cretaceous transition led to prolonged early subaerial exposures during which freshwater flowed efficiently through the upper half of the formation. Through mineralogical stabilization, among other processes, microporosity was preserved in micrites in this interval consisting of clean limestone with thin marl layers. The lower half of the formation, more argillaceous, was not or was only slightly affected by this early meteoric diagenesis, and recrystallization and cementation of micrites occurred during burial diagenesis, involving chemical compaction. Later, during the return to the surface associated to the Cenozoic orogens, another phase of meteoric diagenesis affected the uppermost few metres below the outcropping portions of the formation, but without modifying significantly the previously acquired petrophysical properties. Consequently, an intra-formational boundary was progressively developed at around 75 m (from the top reference). This boundary separates (1) a lower half of the Calcaires du Barrois with dense and tight micrites, showing high Young's modulus values, and a moderate intensity of fractures, from (2) an upper half with microporous micrites showing low Young's modulus values, and almost devoid of fractures. A transitional zone of about 30 m thick, with intermediate properties, sitting above this boundary and below the only thin metre-scale macroporous grainstone level of the formation, accommodated most of the deformation linked to the Cenozoic Western European orogens and is intensively fractured. The current hydrogeological model considers a purely sedimentological boundary to delimit two sub-aquifers within the Calcaires du Barrois Formation. This will have to be reappraised since it is here demonstrated that the real boundary is located significantly higher in the formation and is inherited from a multi-stage diagenetic history. These findings will complement and influence planning for the Industrial Centre's project.

Advanced floodplain mapping: HEC-RAS and ArcGIS pro application on Swat River

AbstractFloods stand out as one of the most devastating environmental threats worldwide resulting in the tragic loss of human lives and significant damage to our essential infrastructure. This study focuses on creating floodplain maps for the two important reaches of Swat River in the Khyber Pakhtunkhwa Province of Pakistan, namely, Kalam–Khwazakhela and Khwazakhela–Chakdara reaches. The Advanced Land Observing Satellite Phased Array Type L-band Synthetic Aperture Radar (ALOS PALSAR) 12.5 m Digital Elevation Model (DEM) data has been used for this purpose. Furthermore, the sensitivity of the flood model was assessed for the Flood 2022 event, considering simulated flood depth, extent, and velocity in relation to various terrains derived from the 12.5-m ALOS PALSAR data. To estimate extreme flows for different return periods (2, 5, 10, 25, 50, and 100 years), the Log Normal (LN), Log Pearson III (LP3), and Generalized Extreme Value (GEV) distributions were employed for the frequency analysis. The GEV distribution turned out to be the best fit for modeling the Swat River for both the Chakdara and Khwazakhela gauge stations. To predict flood levels for the peak floods identified through frequency analysis and for the specific return periods the Hydrologic Engineering Center's River Analysis System (HEC-RAS) 2D simulations were performed. Subsequently the outcomes of this model were used to create floodplain maps using Geographic Information System Professional (ArcGIS Pro) software customized for various return periods. The analysis revealed a linear increase in flood inundation area with longer return periods. The floodplain maps developed hold significant importance for the governing authorities of the Swat region. These maps serve as essential tools for implementing proactive measures against potential infrastructure damage, thereby protecting against economic losses and enhancing public safety. This research effectively combines hydrological modeling and geospatial technology offering practical solutions for managing flood risks. It serves as a valuable guide for making well-informed decisions and promoting sustainable development in flood-prone areas.

Experimental investigation on the hydrodynamic performance of an inverted trapezoidal breakwater

ABSTRACT The wave transmission, reflection, and dissipation characteristics of conventional (trapezoidal (TBs)) and non-conventional (inverted trapezoidal (ITBs) and rectangular (RB)) breakwaters with the same volume and porosity are evaluated under different submergence ratios, wave heights, and wave periods in regular and random waves. The experimental investigation revealed that the ITB shape is the most efficient cross section for reducing wave transmission coefficient (Kt) when the breakwater is submerged or the still water level (SWL) is at the crest of the breakwater, whereas the conventional TB is the least efficient. Compared to the conventional TB, the ITB reduced Kt by 10%–20% under submerged conditions and by 20%–30% when the SWL is at the breakwater crest. Kt < 0.2 is obtained for a relative water depth d/Lp > 0.2, which is suitable for most wave damping applications in the field when the ITB crest is at the SWL or when the crest emerges.

Modulation effect of uniform flow on three-dimensional freak wave generation in arbitrary water depth

In arbitrary water depths, the influence of uniform flow, which includes transverse and longitudinal flows, on the generation of three-dimensional (3D) freak waves is examined. A modified Davey–Stewartson equation is derived using potential flow theory and the multiscale method. This equation describes the evolution of 3D freak wave amplitude under the influence of uniform flow. The relationship between two-dimensional (2D) modulational instability (MI) and the generation of 3D freak waves, as represented by the modified 3D Peregrine Breather solution, is explored. The characteristics of 2D MI depend on the orientation of the longitudinal and transverse perturbations. In shallow waters, the generation of freak waves by MI is challenging due to the minimal orientation difference, and longitudinal flows hardly affect the occurrence of MI. Variations in relative water depth can contribute to forming shallow-water freak waves. In finite-depth waters, oblique modulation leads to MI, whereas in deep and infinite-depth waters, longitudinal modulation gains significance. In environments of finite-depth, deep, and infinite-depth waters, the divergence (convergence) effect of longitudinal favorable (adverse) currents reduces (increases) the MI growth rate and suppresses (facilitates) freak wave generation.

Experimental investigation on a new method for modifying the geometry of a vertical drop edge equipped with a screen on the amount of energy dissipation

Abstract The aim of the current research is to investigate the effect of geometry and different angles (180°, 150°, 120° and 90°) of the edge of a vertical drop with a height of 0.15 m with and without a vertical screen on energy dissipation. The finding showed that the triangulation plane forms a vertical drop at different angles of 180°, 150°, 120° and 90° without a screen that increases the energy dissipation of the drop, which is highest at an angle of 90°, by 50.5%. In the vertical drop with a screen, reducing the angle also leads to a decrease in energy dissipation, so the highest energy dissipation occurs at an angle of 180° with a 45.2% increase in energy dissipation compared to the vertical drop without a screen. The relative depth of the edge and the relative depth of the vertical drop pool of the triangular plane are different at the angle vertex and its wings, in such a way that the relative depth of the edge at the vertex is less than the wings and the relative depth of the pool at the vertex is greater than the wings.

Three-Dimensional Turbulent Simulation of Bivariate Normal Distribution Protection Device

In response to the deficiencies in existing bridge pier scour protection technologies, this paper introduces a novel protective device, namely a normal distribution-shaped surface (BND) protection devices formed by rotating a concave normal curve. A three-dimensional turbulent SST k−ω model is constructed, and physical model experiments of conical surfaces are conducted to validate the mathematical model. The simulation analyzes longitudinal water flow, downflow, vorticity intensity, and shear stress within normal and conical surfaces. The results show that the downflow distribution in front of the pier spans a relative water depth of (−0.45, 0.67), with a peak velocity approximately 70% of the longitudinal flow velocity. Circulation forms within the surfaces, with the main vortex flux inside the BND being 33% lower than that inside the conical surface. The maximum shear stress coefficient inside the BND can reach 9, and the protective surface isolates the bed from the flow to prevent scouring by high shear stress. The velocity gradient at the edge of the surface is small, and the edge shear stress of the 3D normal distribution-shaped surface (BND) protection device is only one-third of that of the conical surface, preventing edge scouring. The large shear stress and its distribution area decrease monotonically with the increase in surface width. When the surface width is four times the diameter, the distribution range of the shear stress coefficient greater than 1 is very small. The study of three-Dimensional turbulence within the BND provides a numerical basis for an anti-scour design.

The heart of an AI

The article presents an analysis centered on the emotional lapses of artificial intelligence (AI) and the influence of these lapses on two critical aspects. Firstly, the article explores the ontological impact of emotional lapses, elucidating how they hinder AI’s capacity to develop a moral sense. The absence of a moral emotion, such as sympathy, creates a barrier for machines to grasp and ethically respond to specific situations. This raises fundamental questions about machines’ ability to act as moral agents in the same manner as human beings. Additionally, the article sheds light on the practical implications within human-machine relations and their effect on human friendships. The lack of friendliness or its equivalent in interactions with machines directly impacts the quality and depth of human relations. This concerningly suggests the potential replacement or compromise of genuine interpersonal connections due to limitations in human-machine interactions.

Potentials of spaceborne imaging spectrometer PRISMA, ASTER, and ALOS-1 PALSAR datasets for mineral mapping and geological controls of mineral deposit in Jahazpur, Rajasthan, India

Palaeoproterozoic rocks of the Jahazpur region are well known for talc mineralization and its mining. The present study attempts to identify and map the talc and associated minerals and their structural control using multi-source remote sensing datasets. Remote Sensing studies were carried out using the relative band depth methods for the ASTER dataset for mapping talc and other associated minerals of the region. Principal Component Analysis (PCA), Independent Component Analysis (ICA), and Minimum Noise Fraction (MNF) were applied to the PRISMA dataset to map the lithology of the region. Along with that, the Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) algorithms map the talc and clay minerals using the PRISMA dataset. ALOS – 1 PALSAR dataset had been utilized to delineate the various lineaments present in the region at different angles. The obtained mineral maps form the ASTER had been validated with results of the PRISMA classified map and showed a good number of similarities. The obtained results from remote sensing have been further validated with the help of field survey and XRD analysis which confirms the presence of talc and clay minerals in the region. The structural pattern of the lineament shows the similarity in the direction orientation with the Jahazpur Thrust. Dolomites and clay minerals were mapped around the talc mining region which suggests that the alteration of these minerals played an important role in the formation of talc. Clay minerals were also mapped there and formed due to the weathering of the granites of Berach and Jahazpur present in the region. Both talc and clay deposits are present at the higher lineament density zones which represents the structural control over the mineralization. Therefore, the mineral deposits of the Jahazpur region are mineralogical and structurally controlled.

The Impact of Relational Depth on Subjective Well-being in Close Relationships in the Community

Relational depth (RD)—moments of profound connection and engagement between two people—is a humanistic–existential construct, showing preliminary association with psychological growth in psychotherapy. This research investigates the impact of RD, alongside relationship satisfaction and emotional intimacy, on subjective well-being in close relationships in the community. Psychometric properties of latent variables were assessed in a stratified online sample of 497 participants in the United Kingdom (47.1% male, 52.1% female, 1% other; mean age 45.7 [ SD = 15.9]; 86.5% white, 7.8% Asian, 3.2% Black, 1.4% mixed and 1% other), followed by lagged regressions, and moderation analyses to assess the role of RD on Personal Well-being Score (PWS). Data were collected at two further time points at 3-month intervals on a stratified subset of participants ( n = 297 and n = 267). RD emerged as a significant predictor of subjective well-being in close relationships in the community and was moderated by emotional intimacy and relationship satisfaction. This study provides the first robust evidence of the relevance and impact of the humanistic–existential construct of RD on well-being beyond a psychotherapy context. This points to the value of practices that can facilitate RD experiences in the community.

A robust nano-indentation modeling method for ion-irradiated FCC single crystals using strain-gradient crystal plasticity theory and particle swarm optimization algorithm

Addressing the challenge of identifying an appropriate set of material and irradiation parameters for accurate simulation models using crystal plasticity finite element method (CPFEM), this study proposes a novel two-stage method for nano-indentation modeling of ion-irradiated face-centered cubic (FCC) materials. It includes implementing the strain-gradient crystal plasticity (SGCP) theory with irradiation effects and the calibration of simulation parameters using the particle swarm optimization (PSO) algorithm with experimental data. The proposed method consists of two stages: establishing CPFEM without irradiation effects in stage 1 and modeling irradiation effects based on CPFEM in stage 2. Modeling the nano-indentation test of ion-irradiated stainless steel 304 (SS304) using real experimental data is conducted to evaluate the efficiency of the proposed method. The accuracy of the calibration method using PSO is verified through comparisons between simulation and experimental results for force-indentation depth and hardness-indentation depth relationships under both unirradiated and irradiated conditions. Moreover, effect of ion-irradiation on the mechanical behavior during the nano-indentation of single crystal SS304 is also examined to demonstrate that the proposed method is a powerful approach for nano-indentation modeling of ion-irradiated FCC single crystals using SGCP theory and the PSO algorithm.

Abstract 4950: Applying fragmentomics profiles of plasma cell-free DNA for breast cancer detection

Abstract The liquid biopsy approach focusing on DNA molecules supports the non-invasive diagnosis of breast cancer. Low-pass whole genome sequencing(lpWGS) for breast cancer detection has been validated for accuracy and cost-effectiveness, especially with copy number variant (CNV) analysis. However, detecting breast cancer with cell-free DNA (cfDNA) CNV was limited by tumor fraction. Utilizing cell-free DNA fragmentation characteristics for cancer detection has shown potential in plasma with high precision and applicability with low tumor fraction. In this study, 217 patients with breast cancer and 10 healthy individuals were enrolled. The cfDNA was extracted and performed using PredicineSCORE, a low-coverage whole genome sequencing assay to identify tumor-specific features. The cfDNA fragmentomics profiles including the coverage at specific regions, length and end-motif of fragment were implemented. We also investigated the copy number variation and the inferred tumor fraction which was adjusted by the Expectation-Maximum (EM) algorithm. Combining, an ensembled machine learning model was constructed for the classification of breast cancer and normal control. We observed a high correlation between tumor fraction and features. The absolute correlation coefficient scores between tumor fraction with the LYL1, MAF, FOXA1, and GRHL2 bonding sites' relative depth were over 0.82, 0.71,0.89,0.87. The insert size ratio of short reads and the CCCA end motif were over 0.77 and 0.72, respectively. We then diluted the tumor samples of tumor fraction at 0.1% to 50% by manually mixing reads from tumor samples into normal samples. By applying the XGBoost algorithm, the performance (F1 score &amp;gt; 0.95) showed a promising ability to distinguish tumors from normal samples. The limit of detection (LOD) was less than 1% which is more sensitive than previously proposed models. Those samples detected mutations with high through panel which can confirm the accuracy of the assay. Our results discovered that profiling the cell-free DNA fragment could facilitate the way of non-invasively detection of breast cancer with high precisions. Citation Format: Yaxin Liu, Shuang Gan, Hang Dong, Haoran Tang, Nan Wang, Xinyu Gui, Anjie Zhu, Ruyan Zhang, Pan Du, Shidong Jia. Applying fragmentomics profiles of plasma cell-free DNA for breast cancer detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4950.

A Foggy Weather Simulation Algorithm for Traffic Image Synthesis Based on Monocular Depth Estimation.

This study addresses the ongoing challenge for learning-based methods to achieve accurate object detection in foggy conditions. In response to the scarcity of foggy traffic image datasets, we propose a foggy weather simulation algorithm based on monocular depth estimation. The algorithm involves a multi-step process: a self-supervised monocular depth estimation network generates a relative depth map and then applies dense geometric constraints for scale recovery to derive an absolute depth map. Subsequently, the visibility of the simulated image is defined to generate a transmittance map. The dark channel map is then used to distinguish sky regions and estimate atmospheric light values. Finally, the atmospheric scattering model is used to generate fog simulation images under specified visibility conditions. Experimental results show that more than 90% of fog images have AuthESI values of less than 2, which indicates that their non-structural similarity (NSS) characteristics are very close to those of natural fog. The proposed fog simulation method is able to convert clear images in natural environments, providing a solution to the problem of lack of foggy image datasets and incomplete visibility data.

Two-parameter wave reflection coefficient for an impermeable breakwater armored with Accropodes

Coastal breakwaters serve a vital role in dissipating wave energy in severe ocean environments and mitigating disastrous impacts of global climate change. As one of the key metrics in evaluating performance of breakwaters, reflection coefficients are usually formulated empirically as a function of either the Iribarren number accounting for wave breaking or the relative water depth measuring wave dispersion. In this work, we conduct a scaled physical model experiment to investigate wave reflection from a horizontally composite breakwater with a steep impermeable slope armored by Accropodes. Tests with specifically designed regular wave conditions produce 400 plus measurements over a grid of Iribarren number and relative water depth to analyze their interplay in jointly determining the reflection coefficients. Empirical formulas in terms of either one or two parameters are proposed through regression analysis for performance evaluation. Error analysis indicates the two-parameter formulas outperform the one-parameter ones with significantly improved predictive skills for the studied breakwater. The two-parameter approach allows complementary influences from the Iribarren number and the relative water depth in fitting the observations and can have broad applications in studies of fluid-structure interactions involving wave reflection, overtopping, transmission, and armor stability, especially when the coastal structures are located outside the shallow-water zone.

Modulational Instability of Nonlinear Wave Packets within (2+4) Korteweg–de Vries Equation

The higher-order nonlinear Schrödinger equation with combined nonlinearities is derived by an asymptotic reduction from the (2+4) Korteweg–de Vries model for weakly nonlinear wave packets for the context of interfacial waves in a three-layer symmetric media. Focusing properties and modulation instability effects are discussed for the considered physical context. Instability growth rate, maximum of the increment and the boundaries of the instability interval are derived in terms of three-layer density stratification, their structure on the parameter planes of relative layer depth, carrier wavenumber and envelope amplitude, are considered in detail.

Supratrochlear artery

Introduction. The supratrochlear artery (STA) is a small vessel with a relatively tiny and quite constant course. The literature describing the STA fails to provide a collective description of the anatomy and neurosurgical applications of the STA. Therefore, we are here to present an overview of anatomy, anatomical variability, and the clinical application of STA. Method. We conducted a literature review in Google Scholar and PubMed medical databases to review the existing studies on STA regarding its anatomy and neurosurgical applications. Results. We identified 18 articles that discuss the anatomical variations and neurosurgical applications of the STA. Certain parameters are used to describe the surgical anatomy of STA, including origin, course, diameter, branches, depth, and distance in relation to the midline and vertical glabellar line. We also discussed certain applications of STA and its importance in neurosurgical reconstruction flaps and the diagnosis of carotid artery disease. Conclusion. Comparable to the supraorbital artery (SOA), the STA is less variable in its anatomical course, and exhibits a more superficial course. The STA has certain important neurosurgical applications through its involvement in reconstruction flaps for the skull base and plays an important role in the diagnosis of carotid artery disease.

Dependence of spectral purity of Gd plasma emission around 6.7 nm on laser irradiation conditions

Gadolinium is a compelling candidate for the next-generation 6.x nanolithography light source. We present a systematically study on the spectral purity at 6.7 nm in the gadolinium laser produced plasma. Variations in extreme ultraviolet spectra are observed over a wide range of laser focal spot sizes and laser pulse energies due to the combined effect of plasma temperature and opacity. When varying laser focal spot size, ionic populations of Gd ions at different electron temperatures were estimated by the collisional-radiative model for the explanation of changes in the spectral profile. When adjusting the laser pulse energy, modifications in the electron density profile were measured through Nomarski interferometry, and the related optical depth was quantified assisted with a one-dimensional radiation transfer model. Results show that, appropriate laser energy and focal spot size are necessary to achieve the high spectral purity, and with a lens with focal length of f = 175 mm and a laser pulse energy of 100 mJ, a spectral purity of Gd plasma up to 3.7% over range of 5.5–10 nm is achieved.