Practical Parameters Research Articles

Value of Pretreatment Inflammation-nutrition Score to Predict Non-response to Neoadjuvant Chemotherapy in Locally Advanced Rectal Cancer

ObjectiveTo investigate the value of pretreatment inflammatory-nutritional biomarkers in predicting the pathological response of locally advanced rectal cancer (LARC) after neoadjuvant chemotherapy (nCT). MethodsThis retrospective study included eligible participants who underwent nCT followed by radical surgery. Pretreatment inflammatory nutritional biomarkers were calculated within one week prior to nCT. Correlations between biomarkers and pathological responses were analyzed. The cut-off values of the pretreatment biomarkers for predicting non-response were determined using receiver operating characteristic (ROC) curve analysis. The inflammation-nutrition score was calculated using the lymphocyte level, neutrophil-to-lymphocyte ratio (NLR), and prognostic nutritional index (PNI). ResultsA total of 235 patients were retrospectively recruited between January 2017 and September 2022. Lower lymphocyte levels, lymphocyte monocyte ratio (LMR), and PNI, and higher NLR and platelet-to-lymphocyte ratio (PLR) were observed in patients without response. Multivariate logistic regression analysis revealed that NLR could independently predict non-response to nCT in patients with LARC. The sensitivity and specificity of the inflammation-nutrition score for predicting nonresponse were 71.2% and 61.7%, respectively. ConclusionThe pretreatment inflammation-nutrition score is a practical parameter for predicting nonresponse to nCT in patients with LARC. Patients with high scores were more likely to respond poorly to nCT.

Determination of operational parameters for the first stage of continuous temperature-phased anaerobic digestion of oily food waste: Influent concentration, hydraulic retention time, pH control and temperature

Anaerobic digestion is promising in both food waste reduction and energy upgrading. However, the intermediates in anaerobic digestion of such an oily food waste, long chain fatty acids, not only have low bioavailability but also significantly threaten operation stability. Temperature-phased anaerobic digestion is an emerging technology in recent years, expected to overcome those issues. Given significance of the first stage of the two-stage process, continuous thermophilic digestion of oily food waste was conducted, with mesophilic digestion operated in parallel as control, to determine practical operational parameters from operation performance and stability. The feeding concentration at approximately 4.50 % of volatile solids was identified to be applicative for a relatively stable operation. Due to slow β-oxidation for long chain fatty acids, hydraulic retention time for the first stage needed longer than 10 d to maintain anaerobes’ survival so that they were not inhibited. In addition to the risk from inhibition, readily acidified risk still existed, and instant pH control was demonstrated to be efficient in maintaining the habitat of microbial metabolism. Compared with no viable bacteria detected under uncontrolled pH, 36.7 % live cells could still be detected under controlled pH. Overall, thermophilic digestion obviously achieved advantages in higher substance degradation and methane production with lower stability risk. The genera Methanosarcina and Methanothermobacter played a significant role, with the ratio at about 2:1. While bacterial viability was not reduced remarkably in preliminary period of inhibition, long-term operation under high lipid loading resulted in its loss.

Lens Checking: How Eye Care Practitioners Verify and Inspect Rigid Contact Lenses

Purpose. The primary focus of this article is to explore the critical aspects of verifying and inspecting RGP contact lens parameters in clinical practice. The verification process is essential to ensure that patients receive lenses with accurate and optimal parameters, thus improving their visual experi- ence and comfort. The article delves into the methods and instruments available to eye care practitioners for verifying key parameters, including back surface radii, total lens diam- eter, lens power, lens thickness, blends, and surface quality. Material and Methods. The discussion centers on the tech- niques and tools employed in the verification and inspection of RGP contact lens parameters. It emphasizes the signifi- cance of maintaining a clean and controlled environment for these assessments. Calibration and error minimization strate- gies are highlighted to enhance measurement accuracy. The article provides insights into device-specific measurements and the importance of averaging measurements to mitigate deviations. Results. The article outlines various procedures for verifying the essential parameters of RGP contact lenses. It covers methods for checking back surface radii, including the use of radiuscopes, keratometers, and corneal topographers. Verifi- cation of lens diameter is detailed with V-shaped measuring gauges, measuring magnifiers, and projection magnifiers. Lens power verification is explored through lensmeters and specialized lensmeter calibration techniques. Finally, the measurement of lens thickness, the inspection of lens edges, and the evaluation of surface quality and blends between different lens zones are addressed. Conclusion. This article underscores the significance of thorough verification and inspection of RGP contact lens parameters in clinical practice. These essential steps ensure that patients receive lenses that meet their specific needs, contributing to improved visual acuity, comfort, and overall ocular health. Eye care practitioners should check their pa- tients’ RGP contact lenses according to the ordered param- eters. By following the described methods and employing appropriate instruments, the fitting and prescribing of rigid gas-permeable contact lenses can be enhanced. Keywords Rigid gas-permeable contact lenses, RGP contact lenses, specifications and tolerances for rigid contact lens parameters, verification and inspection of RGP contact lenses, lens checking

Multi-block alternating direction method of multipliers for ultrahigh dimensional quantile fused regression

In this paper, we consider a quantile fused LASSO regression model that combines quantile regression loss with the fused LASSO penalty. Intuitively, this model offers robustness to outliers, thanks to the quantile regression, while also effectively recovering sparse and block coefficients through the fused LASSO penalty. To adapt our proposed method for ultrahigh dimensional datasets, we introduce an iterative algorithm based on the multi-block alternating direction method of multipliers (ADMM). Moreover, we demonstrate the global convergence of the algorithm and derive comparable convergence rates. Importantly, our ADMM algorithm can be easily applied to solve various existing fused LASSO models. In terms of theoretical analysis, we establish that the quantile fused LASSO can achieve near oracle properties with a practical penalty parameter, and additionally, it possesses a sure screening property under a wide class of error distributions. The numerical experimental results support our claims, showing that the quantile fused LASSO outperforms existing fused regression models in robustness, particularly under heavy-tailed distributions.

Design charts for hydraulic twister based aircraft arrester gear

In this article, arrestment of an aircraft by a hydraulic twister based system is modeled and reduced to simple design charts. We are primarily interested in performance parameters like maximum deceleration, run-out distance, and maximum tape force. We first present a simplified mechanical model for the system. Some analytical progress is possible with the governing nonlinear differential equation, yielding expressions for velocity and acceleration in terms of displacement. The system has only two nondimensional parameters. This allows us to present simple design charts for the performance parameters. The same approach is extended to secondary performance parameters namely maximum jerk and the time at which maximum deceleration occurs. We choose some practical parameter sets and demonstrate the use of our charts. These charts can be used for design calculations and quick performance prediction of an arresting gear design for different weight classes of aircraft and practical initial velocities.

In situ multi-perspective scanning of 3D particle deposition on flat plates with film cooling and determination of practical model parameters

A practical strategy for three-dimensional morphology measurement in the particle deposition process is of great importance to deepen the understanding of deposition physical processes. Due to the methodology limitations, it is difficult to obtain the formation process of deposition morphology. In this work, an in situ multi-perspective scanning (MPS) method using structured light was developed to capture the formation process of deposits. The point cloud registration algorithm was adopted to reconstruct the deposition morphology. Based on the validation results of Vernier caliper, the MPS method provides an uncertainty of ±0.056 mm at 4 mm. To verify the potential application of in situ measurement in gas turbine diagnostics, MPS method was preliminarily applied to the flat plate test with film cooling in particle-laden flow. The application demonstrated that this method successfully reconstructed the deposition morphology on a flat plate in the presence of film cooling. Furthermore, the obtained morphology results revealed that deposition roughness lied in the 0.35–0.56 mm and increased with an increase of blowing ratio. Additional comparisons with film cooling effectiveness showed the deposition distribution was related to the film cooling process. The detailed three-dimensional (3D) deposition morphology determined the mean curvature and mass of deposits, which may improve the prediction accuracy of deposition models in numerical simulations.

Recent guidelines addressing chronic rhinosinusitis with nasal polyps: practical aspects.

Chronic rhinosinusitis (CRS) is common in adults. It is diagnosed based on a high index of suspicion alongside objective means of assessing sinus inflammation. Determining the impact of CRS on patient quality of life is an important starting point for discussions regarding treatment, and is critical for longitudinal assessment of response to specific treatments. CRS can be further categorized by the presence or absence of nasal polyps. Recent Joint Task Force on Practice Parameters Grading of Recommendations Assessment, Development, and Evaluation guidelines for the management of CRS with nasal polyps (CRSwNP) focused on 3 treatment options: intranasal corticosteroids with multiple delivery methods, biologics (monoclonal antibodies targeting type 2 inflammation), and aspirin therapy after desensitization, which only applies to the subset of patients with CRSwNP who experience acute respiratory reactions following nonsteroidal anti‑inflammatory drug ingestion. The authors of the guidelines made conditional recommendations in favor of each of these 3 treatment options, highlighting the importance of shared decision‑making when choosing appropriate therapy for individuals with CRSwNP.

Novel Echocardiographic Measurements of Right Ventricular-Pulmonary Artery Coupling in Predicting the Prognosis of Precapillary Pulmonary Hypertension.

Currently, there are many parameters with proven prognostic significance in pulmonary hypertension (PH). Recently, the parameters defining right ventricular-pulmonary artery coupling (RVPAC) have gained clinical importance. In our study, we investigated the prognostic potential of previously known single echocardiographic parameters and new parameters reflecting RVPAC in patients with precapillary PH. Our study aimed to evaluate the prognostic value of selected echocardiographic parameters and the neutrophil-lymphocyte ratio (NLR) in adults with precapillary PH. This study included 39 patients (74% women; average age, 63 years) with precapillary PH: pulmonary arterial hypertension (PAH) and chronic thromboembolic PH (CTEPH). The mean follow-up period was 16.6 ± 13.3 months. Twelve patients (31%) died during the observation time. We measured several echocardiographic parameters, which reflect right ventricular function, pulmonary hemodynamics, and RVPAC. To assess disease progression and the patient's functional capacity, the World Health Organization functional class (WHO FC) was determined. The patient's physical capacity was also evaluated using the 6 min walk test (6MWT). The analysis included values of the N-terminal prohormone brain natriuretic peptide (NT-proBNP) and NLR. TAPSE × AcT and TAPSE/sPAP were shown to statistically and significantly correlate with PH predictors, including WHO-FC, 6MWT, and NT-proBNP. Univariate Cox proportional hazards regression analysis revealed that AcT, TAPSE, mPAP, TAPSE/sPAP, RAP, TRPG/AcT, TAPSE × AcT, and NLRs are good predictors of mortality in patients with PH. In addition, the ROC curve analysis showed that TAPSE × AcT is a better predictor of PH-related deaths than TAPSE/sPAP and TAPSE alone. In our study, patients with TAPSE × AcT values < 126.36 had shorter survival times (sensitivity = 72.7%; specificity = 80.0%). TAPSE × AcT is a novel, promising, and practicable echocardiographic parameter reflecting RVPAC, which is comparable to TAPSE/sPAP. Moreover, TAPSE × AcT can be a useful parameter in assessing the severity and prognosis of patients with precapillary PH.

Point Cloud-Based Smart Building Acceptance System for Surface Quality Evaluation

The current expansion of building structures has created a demand for efficient and smart surface quality evaluation at the acceptance phase. However, the conventional approach mainly relies on manual work, which is labor-intensive, time-consuming, and unrepeatable. This study presents a systematic and practical solution for surface quality evaluation of indoor building elements during the acceptance phase using point cloud. The practical indoor scanning parameters determination procedure was proposed by analyzing the project requirements, room environment, and apparatus. An improved DBSCAN algorithm was developed by introducing a plane validation and coplanar checking to facilitate the surface segmentation from the point cloud. And a revised Least Median of Square-based algorithm was proposed to identify the best-fit plane. Afterwards, the flatness, verticality, and squareness were evaluated and depicted using a color-coded map based on the segmented point cloud. The experiment on an apartment showcases how the system improves the information flow and accuracy during building acceptance, resulting in a potentially smart acceptance activity.

Hansen solubility parameters sphere calculations and thermodynamic model fitting of two novel copper complexes supported by bis(imino)pyridine ligands

In this paper, two novel five-coordinated copper(II) metal complexes, [2,6-(ArN = CMe)2C5H3NCuCl2] (Ar = 2-EtC6H4, L1CuCl2; Ar = 4-EtC6H4, L2CuCl2), bearing bulky 2,6-bis[1-(2-ethylphenylimino)ethyl]pyridine ligands L1 (L1 = 2,6-(ArN = CMe)2C5H3N, Ar = 2-EtC6H4), 2,6-bis[1-(4-ethylphenylimino)ethyl]pyridine ligands L2 (L2 = 2,6-(ArN = CMe)2C5H3N, Ar = 4-EtC6H4) have been synthesized and characterized, and the thermodynamic properties of these complexes are reported in a variety of mono-solvents. The copper(II) metal complexes based on bis(imino)pyridine are widely used in catalysis, photoelectric material, biopharmaceuticals and other fields. In this paper, the solubility of L1 and L2 in four solvents, the solubility of L1CuCl2 in four solvents and the solubility of L2CuCl2 in five solvents were studied by static analysis. The solubility of these compounds was investigated in a certain temperature range to provide data to support the selection of optimal solvents for organic reactions, coating and crystallization separations. Hansen solubility parameters (HSPs) were used to explain the dissolution behavior of solutes and were found to be consistent with experimentally measured results. Moreover, the values of HSPs for L1CuCl2 and L2CuCl2 lacking Cu data were simulated by the Hansen Solubility Parameters in Practice (HSPiP) software, which allowed the prediction of solvents with good dissolution behavior. The values of total solubility parameter of Hildebrand (δ) for L1CuCl2 and L2CuCl2 are 24.5 and 23.0, respectively. Besides, solubility properties of L1CuCl2 and L2CuCl2 in two solvent mixtures at different percentages were predicted. In addition, seven thermodynamic models were used to correlate the solubility data. For L1 and L2, Polynomial models fit better with an average absolute relative deviation (ARD) less than 1 %; for L1CuCl2 and L2CuCl2, Polynomial model fits best (ARD < 1 %). In addition, the enthalpy–entropy compensation relationship in the dissolution process was analyzed by calculating the thermodynamic parameters of the substances, and the results showed that the dissolution process of L1 and L2 was an enthalpy-driven heat absorption process.

Creep Properties and Creep Modelling of Guilin Red Clay

In order to explore the creep characteristics of red clay under different pressures, the stress–strain curve and stress–strain–time curve of red clay under different pressures were obtained, and the triaxial shear and creep characteristics of red clay under different pressures were analysed. A triaxial shear test and creep test were carried out on red clay from Guilin as the research object under different pressures. The results show that: ➀ the cohesion and the angle of internal friction of red clay from Guilin, obtained from a triaxial shear test, are 57.20 kPa and 22.47°, respectively; ➁ according to the physical meaning of the parameters of the Burgers creep model, a simple and practical parameter inversion method is proposed, which can be used to obtain the parameters of the Burgers model for red clay under different perimeter pressures and differing deviatoric stress; and ➂ when comparing the calculation results with the test results, the correlation coefficients R2 of the two are above 0.9, with a good fitting effect, so the model can accurately describe the creep characteristics of red clay from Guilin. This study can provide a theoretical basis and technical support for engineering construction in the red clay area of Guilin.

Design and Analysis of an Input–Output Linearization-Based Trajectory Tracking Controller for Skid-Steering Mobile Robots

This manuscript presents a control law based on the kinematic control concept and the input–output linearization approach. More specifically, the given approach has the structure of a two-loop controller. A rigorous closed-loop system analysis is presented by using known theory on perturbed systems. By assuming that the desired velocity in the body frame is persistently exciting, the uniform bound of the tracking error in earth coordinates is ensured. A simulation study using practical mobile robot parameters shows the viability of the introduced approach. In addition, two known trajectory tracking controllers are simulated in order to compare the performance of the proposed technique. Better tracking accuracy is obtained with the proposed control approach, even if uncertainties in the knowledge of the friction coefficients are presented.

Deadbeat Predictive Current Control for Surface-Mounted Permanent-Magnet Synchronous Motor Based on Weakened Integral Sliding Mode Compensation

Deadbeat predictive current control (DPCC) has excellent dynamics and can achieve current control with less computational effort. However, its control performance relies on the precision of the parameters of the motor. Current static error will be generated and control performance will be decreased when the predictive model parameters do not correspond to the practical parameters of the motor. In this article, a weakened integral sliding mode compensation method is proposed which converts the current error into a voltage compensation term and adds it to the prediction control output to effectively compensate for the steady-state error. In addition, a boundary layer is introduced to weaken the integral so as to solve the problems of integral saturation and overshoot caused by the introduction of the integral term when the error is large. Moreover, weight factors are introduced to optimize the feedback current, which enhances the robustness of the system. In the end, the effectiveness of this method is verified via simulation and experimental results.

Control system design for a class of non-cascade nonlinear under-actuated systems with an application to a rotary crane system

For cascade under-actuated systems, several effective control methods have been established. For non-cascade under-actuated systems with one under-actuation degree, several control methods, such as cascade transformation and energy-based control, have been studied. For non-cascade nonlinear under-actuated systems with two or more under-actuation degrees, approximate linearization is necessary to apply these methods, thus only stability at the equilibrium point has been guaranteed. In this paper, control system design and stability analysis are presented for a class of non-cascade nonlinear under-actuated systems with two or more under-actuated degrees. The stability condition obtained in the analysis is a conservative sufficient condition because norm estimation is used. Based on the sufficient condition, we propose a stabilization parameter search algorithm to numerically obtain the practical control parameters. The proposed algorithm is applied to a rotary crane system as one of the nonlinear systems with two under-actuated degrees. The effectiveness of the proposed control system design is verified by numerical simulations and experiments.

A novel electrochemical method determining pKa and transport parameters of buffers using acid-base transport limitation response

Dissociation constant (logarithmic form, pKa) and diffusion coefficient (D) are two fundamental physical parameters for weak acids and bases (buffers). Their effortless determinations from one method are not available yet. Herein, we propose an innovative method to determine pKa and D values based on a brand-new principle of electrochemical acid-base transport limitation (eABTL). The significance of eABTL lies in its ability to relate inert buffers to electrode reactions, enabling the acquisition of electrochemical responses for inert species. Acid-base transport limiting current (jl) is the only variable that needs to be measured. The pKa and transport coefficient (m) are determined from the relationship of jl vs. solution pH and jl vs. buffer concentration, respectively. Three ways are available for D determinations by introducing the expressions of diffusion layer thickness. The method is demonstrated using rotating disc electrodes to implement hydrogen evolution reaction. The pKa, m and D values exhibit good repeatability in multiple determinations. A well-defined electrode geometry is necessary for accurate D determination. This method can be developed to a family of methods with the advantages for fast estimating practical parameter values of buffers.

Design and Control of an Aerial Manipulator With Invariant Center of Gravity for Physical Interaction

Abstract The deployment of manipulators enhances the versatility and flexibility of unmanned aerial vehicles (UAVs) in aerial physical interaction tasks but also challenges their designs and controls due to variations in the center of gravity (CoG), moment of inertia, and reaction wrenches. This work presents a novel design of a two-degree-of-freedom dual-tool manipulator with invariant-center-of-gravity (ICoG) property. The ICoG conditions are strictly deduced, and a practical optimization-based parameter tuning method is proposed. A novel adaptive extended state observer (AESO)-based impedance control method is developed with actuator dynamics taken into account. The AESO can estimate and compensate for both the lumped disturbance, including the influences of moment-of-inertia variation and counter torque, and the unmeasurable states for the controller. In addition, a switching adaptive law is proposed to attenuate the peaking phenomenon under high observer gains. The impedance controller is designed using an auxiliary impedance tracking error to overcome the difficulty of the increased system order. The Lyapunov approach is used to evaluate the stability of the entire system. The proposed approach is implemented on a fully actuated hexarotor with a prototype of the ICoG manipulator. Comparative experiments are conducted to validate the effectiveness and advantages of the proposed design and control methods.

A new multi‐objective optimization of refrigeration cycles (Case study: “Optimization of transcritical carbon dioxide cycle”)

AbstractFor store and maintain products, ingredients, and other perishables at a safe temperature, there is a growing need for low‐temperature refrigeration systems. In this study, a new multi‐objective exergetic criterion is proposed for the optimization of refrigeration cycles, the conventional coefficient of performance (COP) maximization method results in high evaporator temperature, which is in contrast with the philosophy of the invention and design of refrigeration cycles. Thus, it is not a suitable platform for comparing different refrigeration cycles. This research aims to define a practical performance analysis parameter for designing and comparing refrigeration cycles. The novelty of this research is incorporating the impact of evaporator temperature into the COP concept. A performance comparison of the multi‐objective optimization is drawn with that of the maximum COP state on a transcritical carbon dioxide refrigeration cycle. According to the comparison, the evaporator temperature at the optimal state of multi‐objective exergetic optimization was 44 K lower than that of the maximum COP state, which demonstrates the excellent performance of the method. The results of the new multi‐objective exergetic optimization can be used to design low‐temperature evaporation refrigeration cycles. In the end, the flowchart of the suggested performance optimization is presented. Exergy of power at the optimal point of exergetic optimization is about 77% higher than the maximum COP. A comparison of the results obtained from maximum performance coefficient with optimal point of exergetic optimization suggests that the performance coefficient at optimum state of exergetic optimization is about 58% lower than the maximum COP.

Ocean thermal energy conversion (OTEC) system driven with solar-wind energy and thermoelectric based on thermo-economic analysis using multi-objective optimization technique

In the present study, we investigated a multiple energy generation system based on the use of solar, wind and ocean thermal energy for the study area with high renewable energy potential. In this study, all existing capacities in coastal areas (wind, sun, ocean temperature difference) are used to design a renewable system. The present system consists of subsystems including organic Rankin cycle (ORC), wind turbine, thermoelectric, heat exchanger and flat panel solar collector. EES thermodynamic software has been used to model the system and obtain thermodynamic results. The system designed for the city of Bushehr, which has good ocean thermal energy, wind energy and solar radiation potential, has been studied. The most important effective and practical parameters in the proposed system are collector area, solar radiation, and wind turbine speed. The results of the investigation of the system in Bushehr City showed that the production power of the system is 4,840,913.8 and 1,138,957.02 kWh compared to the climate changes. Also, the amount of freshwater produced by the system is 103,495.99 and 429,080.51 m3/h compared to the climate changes. Finally, in order to optimize the designed system, the response level multi-objective optimization method has been used to find the best set of objective functions and decision variables. The two objective functions of this optimization included the exergy efficiency of the whole system and the system cost rate. The most optimal value of exergy efficiency was 13.25% and the cost rate was 72.17 $/hour.

Dose Rate Assessment of Spot-Scanning Very High Energy Electrons FLASH Radiotherapy Driven by Laser Plasma Acceleration

This study assesses the dose rate delivered by the spot-scanning VHEE beams generated by laser plasma acceleration and discusses the feasibility and beam requirements for FLASH-RT. Different types of dose rate metrics (averaged-dose-rate (ADR), dose-averaged dose rate (DADR), and dose-threshold dose rate (DTDR)) in the spot-scanning situation are considered. Theoretical analysis and Monte Carlo simulations are performed to quantify the dose rate distribution for the water phantom and investigate the influence of beam parameters. All the beam parameters are derived from the experimental results. At a much lower pulse repetition rate of 5 Hz, ADR can only reach a dose rate at the magnitude of 10^-1 Gy/s, and the FLASH-RT dose rate (40 Gy/s) could be reached when the high-power laser's working repetition rate is kilo-Hertz. Different from ADR, DADR and DTDR are independent of the scanning path, and they can reach the ultra-high dose rate even exceeding 10^14 Gy/s. Meanwhile, the ultrashort electron bunch can be stretched during the scattering in the water, resulting in the dependence of DADR and DTDR on the penetration depth. DADR decreases exponentially from 10^14 Gy/s at the surface to 10^11 Gy/s at 15 cm depth. Both the charge per shot and angular spread are important parameters in the dose rate calculation. The distinct results among these 3 dose rate metrics are due to their correlations with the averaged beam current and instantaneous current. This study explored the practical beam parameters for preclinical use and provided guidance in designing LPA for the future spot-scanning VHEE FLASH-RT.

Quantifying the Impact of the Surface Roughness of Hexagonal Ice Crystals on Backscattering Properties for Lidar‐Based Remote Sensing Applications

AbstractImpacts of small‐scale surface irregularities, or surface roughness, of atmospheric ice crystals on lidar backscattering properties are quantified. Geometric ice crystal models with various degrees of surface roughness and state‐of‐the‐science light‐scattering computational capabilities are utilized to simulate the single‐scattering properties across the entire practical size parameter range. The simulated bulk lidar and depolarization ratios of polydisperse ice crystals at wavelength 532 nm are strongly sensitive to the degree of surface roughness. Comparisons of these quantities between the theoretical simulations and counterparts inferred from spaceborne lidar observations for cold cirrus clouds suggest a typical surface‐roughness‐degree range of 0.03–0.15 in the cases of compact hexagonal ice crystals, which is most consistent with direct measurements of scanning electron microscopic images. To properly interpret lidar backscattering observations of ice clouds, it is necessary to account for the degree of surface roughness in light‐scattering computations involving ice crystals.