Journal articles: 'Silt Density Index (SDI)'

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Nahrstedt, A., and J. Camargo-Schmale. "New insights into silt density index and modified fouling index measurements." Water Supply 8, no. 4 (October 1, 2008): 401–11. http://dx.doi.org/10.2166/ws.2008.087.

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In order to investigate the accuracy and reproducibility of the parameters SDI (silt density index) and MFI (modified fouling index), tests in diverse conditions were performed: with three different types of filter holder, two microfilter pore sizes, with and without permeate spacer and with two foulants (alginate as organic foulant and silica flour as the particulate). Additionally the effect of pressure on fouling indices was analysed. It was concluded, that there is a need to define more boundary conditions in the ASTM standard (exact type of filter holder, exact type of membrane, start conditions) for the SDI to achieve a parameter with reliable and comparable values. But in comparison to MFI, SDI seems to be a more robust parameter for a use in practice pertaining to the influence of a feed pressure level and the effective membrane area. The MFI gives more insights in acting mechanisms and offers advantages for research. It shows a correlation to a concentration of particulate or organic foulants. Like the SDI, it is necessary to define and standardize exact boundary conditions for the MFI tests (classified by the use of MF, UF or NF filter media).

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Wei, Chun-Hai, Stephanie Laborie, Roger Ben Aim, and Gary Amy. "Full utilization of silt density index (SDI) measurements for seawater pre-treatment." Journal of Membrane Science 405-406 (July 2012): 212–18. http://dx.doi.org/10.1016/j.memsci.2012.03.010.

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Prihasto, N., and Seung-Hyun Kim. "The sensitivity of SDI and MFI to a change in particle concentration and properties under saline conditions." Journal of Water Reuse and Desalination 2, no. 3 (September 1, 2012): 140–48. http://dx.doi.org/10.2166/wrd.2012.064.

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The sensitivity of existing fouling indices of SDI (silt density index) and MFI (modified fouling index) to a change in particle concentration and properties was evaluated in this study. The MFI formula predicts an increased fouling tendency when the particle concentration increases and the particle size and density decrease. Consequently, concentration, size and density were selected as parameters to examine. For this purpose, silica particles and Aldrich humic acid (HA) were selected as target foulants because of the substantial difference in their size and density. According to this study, both SDI and MFI were sensitive to a change in particle properties of size and density, while MFI was more sensitive to a change in particle concentration than SDI. It is also found that the fouling tendency could be represented better by separate evaluation of T0 and T15 than SDI, at which the ratio of T0 and T15 is evaluated. T15 is found to be as sensitive as the MFI for both silica suspension and HA solution. The saline condition increased the fouling index. MFI and T15 were sensitive to a change in ionic strength. When inorganic and organic foulants were mixed, their relative proportion determined the fouling index values.

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Park, C., H. Kim, S. Hong, S. Lee, and S. I. Choi. "Evaluation of organic matter fouling potential by membrane fouling index." Water Supply 7, no. 5-6 (December 1, 2007): 27–33. http://dx.doi.org/10.2166/ws.2007.130.

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The membrane fouling index, widely used in the reverse osmosis (RO) membrane industry, is developed mainly to assess the fouling potential of particulate matter. However, the fouling potential by organic matter should also be accurately evaluated as the productivity loss by organic fouling is often more severe than particle fouling, despite its low concentration in feed water. This study was performed to investigate the influence of organic characteristics and feed water solution chemistry on the membrane fouling index, such as the silt density index (SDI). The results showed that the feed solution chemistry (i.e. pH, ionic strength and hardness) affected the SDI values of organic rich feed water to some degree. In addition, Aldrich humic acid (AHA) exhibited higher fouling potential by SDI than Suwannee river humic acid (SRHA), emphasising the importance of organic properties. Lastly, it is shown that although SDI values measured were the same, the degree of NOM fouling was significantly different for the membranes with different surface properties.

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Takeuchi, K., K. Matsui, Y. Ito, Y. Goda, I. Hamano, and N. Ukawa. "Analysis of the filtration curve and the effect of temperature on silt density index (SDI)." Desalination and Water Treatment 57, no. 45 (December 18, 2015): 21364–76. http://dx.doi.org/10.1080/19443994.2015.1123653.

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Rachman, R. M., N. Ghaffour, F. Wali, and G. L. Amy. "Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems." Desalination and Water Treatment 51, no. 4-6 (January 2013): 1091–103. http://dx.doi.org/10.1080/19443994.2012.699448.

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Habib, Muddasar, Unsia Habib, Abdul Rehman Memon, Usman Amin, Zahid Karim, Amad Ullah Khan, Sayed Naveed, and Sultan Ali. "Predicting colloidal fouling of tap water by silt density index (SDI): Pore blocking in a membrane process." Journal of Environmental Chemical Engineering 1, no. 1-2 (June 2013): 33–37. http://dx.doi.org/10.1016/j.jece.2013.03.005.

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Riverol, C., and M. V. Pilipovik. "Prediction of the behaviour of the Silt Density Index (SDI) in the Caribbean Seawater and its impact on RO desalination plants." Desalination 268, no. 1-3 (March 2011): 262–65. http://dx.doi.org/10.1016/j.desal.2010.09.049.

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Abushaban, Almotasembellah, Sergio G. Salinas-Rodriguez, Moses Kapala, Delia Pastorelli, Jan C. Schippers, Subhanjan Mondal, Said Goueli, and Maria D. Kennedy. "Monitoring Biofouling Potential Using ATP-Based Bacterial Growth Potential in SWRO Pre-Treatment of a Full-Scale Plant." Membranes 10, no. 11 (November 21, 2020): 360. http://dx.doi.org/10.3390/membranes10110360.

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Several potential growth methods have been developed to monitor biological/organic fouling potential in seawater reverse osmosis (SWRO), but to date the correlation between these methods and biofouling of SWRO has not been demonstrated. In this research, the relation between a new adenosine triphosphate (ATP)-based bacterial growth potential (BGP) test of SWRO feed water and SWRO membrane performance is investigated. For this purpose, the pre-treatment of a full-scale SWRO plant including dissolved air flotation (DAF) and two stage dual media filtration (DMF) was monitored for 5 months using BGP, orthophosphate, organic fractions by liquid chromatography coupled with organic carbon detection (LC-OCD), silt density index (SDI), and modified fouling index (MFI). Results showed that particulate fouling potential was well controlled through the SWRO pre-treatment as the measured SDI and MFI in the SWRO feed water were below the recommended values. DAF in combination with coagulation (1–5 mg-Fe3+/L) consistently achieved 70% removal of orthophosphate, 50% removal of BGP, 25% removal of biopolymers, and 10% removal of humic substances. Higher BGP (100–950 µg-C/L) in the SWRO feed water corresponded to a higher normalized pressure drop in the SWRO, suggesting the applicability of using BGP as a biofouling indicator in SWRO systems. However, to validate this conclusion, more SWRO plants with different pre-treatment systems need to be monitored for longer periods of time.

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Dias, Isabelli N., Ana C. Cerqueira, Geraldo L. Sant'Anna, and Marcia Dezotti. "Oil refinery wastewater treatment in biofilm reactor followed by sand filtration aiming water reuse." Journal of Water Reuse and Desalination 2, no. 2 (June 1, 2012): 84–91. http://dx.doi.org/10.2166/wrd.2012.022.

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Oil refinery wastewater was sequentially treated in a moving-bed biofilm reactor (MBBR) and a slow-rate sand filter (SF) in order to obtain an effluent with adequate characteristics for downstream reverse osmosis (RO) operation. Experiments were conducted in bench scale units and the results showed that the MBBR was able to remove 90% chemical oxygen demand (COD), 75% NH4+, 95% phenols, operating with a hydraulic retention time (HRT) of 9 h. Additional removal of COD (15–40%) and ammonia (30–60%) was achieved in the slow-rate SF that was also effective for removing microorganisms. The silt density index (SDI) of the treated wastewater (4.5) was below the maximum limit recommended for RO operation. The quality of the effluent from the combined treatment system (MBBR+SF) was already adequate for cooling tower make-up. The RO produced an effluent with quality compatible with that required for use in boilers.

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Koo, Chai Hoon, Abdul Wahab Mohammad, Fatihah Suja', and Meor Zainal Meor Talib. "Comparative Assessment of Membrane Fouling Propensity Using Colloidal Silica as Foulant." Applied Mechanics and Materials 209-211 (October 2012): 1995–98. http://dx.doi.org/10.4028/www.scientific.net/amm.209-211.1995.

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Other than silt density index (SDI), modified fouling index (MFI) is claimed as one of most useful fouling predictive tools in the practice of reverse osmosis. In this study, the effect of colloidal silica particles on the MFI value with the presence of crossflow sampler (CFS) cell at the upstream of MFI setup was systematically investigated. Colloidal silica with the particle size ranging from 70-100 nm was used as the model foulant in this experiment. The feed silica suspension was 0, 50, and 200 mg/L. The effect of membrane pore size as the test membrane in the dead-end cell on the fouling indices was also studied. Polyvinylidene fluoride (PVDF) membranes with molecular weight cut-offs of 150 and 100 kDa were employed. As predicted, the experiment results demonstrated that the fouling indices increased significantly as the feed silica concentration increased. The CFS-MFI values were always lower than the MFI in all the fouling index tests due to the shear force effect generated under the crossflow filtration mode. The fouling index generated from PVDF100 was higher than that of PVDF150 due to the retention of smaller particles. For this reason, PVDF100 membrane was preferred to be used as the test membrane for fouling index tests using colloidal silica over the PVDF150.

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Wang, Hai Xia, and Peng Ji. "Extending Tertiary Treated Municipal Wastewater as Boiler Feed-Water via a Dual Membrane CUF/RO Process." Advanced Materials Research 726-731 (August 2013): 2476–82. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.2476.

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The objective of this work is to conduct feasibility studies on water treatment for boiler feeding water use from treated municipal wastewater effluent using a pilot dual continuous ultrafiltration - reverse osmosis (CUF/RO) membrane process with the capacity of 15m3/h. A CUF membrane from HYDRAcap and LFC3-LD RO membrane were used in this study. The CUF unit and RO unit were operated at over 97% and 75-80% water recovery, respectively. The results indicate that CUF process is not only capable of reducing organic and nutrient pollutants but also achieves a silt density index (SDI) less than 2, turbidity of less than 0.47NTU which is suitable for RO treatment. Rejection of the RO unit in terms of average conductivity, COD, hardness, alkaline, NH4+-N, TN, TP were higher than 98.2%, 97.9%, 99.8%, 97.9%, 93.9%, 95.1% and 75%, respectively. Other parameters also can match the quality of high-grade water for use in the boiler industry except pH. Finally, a cost comparison between dual membrane and ion-exchange process showed annual savings of more than 33000000 CNY can be possible.

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Muhamad Ng, Sabrina Ng, Syazwani Idrus, Amimul Ahsan, Tuan Nurfarhana Tuan Mohd Marzuki, and Siti Baizura Mahat. "Treatment of Wastewater from a Food and Beverage Industry Using Conventional Wastewater Treatment Integrated with Membrane Bioreactor System: A Pilot-Scale Case Study." Membranes 11, no. 6 (June 21, 2021): 456. http://dx.doi.org/10.3390/membranes11060456.

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This study compares the performance of the Hollow Fiber (HF) and Flat Sheet (FS) types of membrane bioreactors (MBRs) for the treatment of food and beverage (F&B) industry wastewater in a pilot-scale study of a wastewater treatment plant (WWTP). HF and FS membrane configurations were evaluated at two different Mixed Liquor Suspended Solid (MLSS) levels: 6000 mg/L and 12,000 mg/L. The performance of each configuration was evaluated in terms of Chemical Oxygen Demand (COD) and Total Suspended Solid (TSS) removals for effluent quality measurement. The transmembrane pressure (TMP), flux rate, and silt density index (SDI) were monitored and calculated for membrane fouling assessment. The results show that the rejection rates of COD and TSS for HF and FS membrane types were more than 84% for the two different MLSS levels. During the study, the HF membrane recorded 0.3 bar transmembrane pressure, which complies with the recommended range (i.e., two to three times of chemical cleaning). On the other hand, the FS membrane operates without chemical cleaning, and the TMP value was below the recommended range at 0.2 bar. It was found that the flux values recorded for both the HF and FS systems were within the recommended range of 40 L/m2/h. Analysis of SDI revealed that the calculated index ranged between 1 and 2.38 and was within the allowable limit of 3. Both types of MBR consistently achieved an 80% to 95% rejection rate of COD and TSS. Effluent quality measurement of treated F&B wastewater in this pilot-scale study using a WWTP integrated with an MBR indicated a good achievement with compliance with the Malaysia industrial effluent discharge standards.

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Miyoshi, T., Y. Takahashi, T. Suzuki, R. Nitisoravut, and C. Polprasert. "Treatment of highly-colored surface water by a hybrid microfiltration membrane system incorporating ion-exchange." Water Supply 19, no. 3 (July 13, 2018): 855–63. http://dx.doi.org/10.2166/ws.2018.132.

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Abstract This study investigated the performance of a hybrid membrane filtration system to produce industrial water from highly-colored surface water. The system consists of a membrane filtration process with appropriate pretreatments, including coagulation, pre-chlorination, and anion exchange (IE) process. The results of the pilot-scale experiments revealed that the hybrid system can produce treated water with color of around 5 Pt-Co, dissolved manganese concentration of no more than 0.05 mg/L, and a silt density index (SDI) of no more than 5 when sufficient coagulant and sodium hypochlorite were dosed. Although the IE process effectively reduced the color of the water, a moderate increase in the color of the IE effluent was observed when there was a significant increase in the color of the raw water. This resulted in a severe membrane fouling, which was likely to be attributed to the excess production of inorganic sludge associated with the increased coagulant dosage required to achieve sufficient reduction of color. Such severe membrane fouling can be controlled by optimising the backwashing and relaxation frequencies during the membrane filtration. These results indicate that the hybrid system proposed is a suitable technology for treating highly-colored surface water.

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Fitobór, Karolina, and Bernard Quant. "Is the Microfiltration Process Suitable as a Method of Removing Suspended Solids from Rainwater?" Resources 10, no. 3 (March 2, 2021): 21. http://dx.doi.org/10.3390/resources10030021.

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Due to climate change and anthropogenic pressure, freshwater availability is declining in areas where it has not been noticeable so far. As a result, the demands for alternative sources of safe drinking water and effective methods of purification are growing. A solution worth considering is the treatment of rainwater by microfiltration. This study presents the results of selected analyses of rainwater runoff, collected from the roof surface of individual households equipped with the rainwater harvesting system. The method of rainwater management and research location (rural area) influenced the low content of suspended substances (TSS < 0.02 mg/L) and turbidity (< 4 NTU). Microfiltration allowed for the further removal of suspension particles with sizes larger than 0.45 μm and with efficiency greater than 60%. Granulometric analysis indicated that physical properties of suspended particles vary with the season and weather. During spring, particles with an average size of 500 μm predominated, while in autumn particles were much smaller (10 μm). However, Silt Density Index measurements confirmed that even a small amount of suspended solids can contribute to the fouling of membranes (SDI > 5). Therefore, rainwater cannot be purified by microfiltration without an appropriate pretreatment.

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Rezaei, Leila, Mohsen Dehghani, Amir Hesam Hassani, and Vali Alipour. "Seawater reverse osmosis membrane fouling causes in a full scale desalination plant; through the analysis of environmental issues: raw water quality." Environmental Health Engineering and Management 7, no. 2 (July 6, 2020): 119–26. http://dx.doi.org/10.34172/ehem.2020.14.

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Background: Membrane clogging is one of the most important problem for desalination plant operators in Iran, therefore, this study was conducted to investigate the main causes of this problem using field analysis. Methods: In this study, six continuous membranes in a reverse osmosis (RO) pressure vessel under the 33-month service period (April 2017 to November 2019) were selected. The membranes were analyzed through visual evaluation of the outer and inner membrane surface, analyzing the damages and physical harms, oxidative stress tests, iron spot test, fouling chemical analysis using loss on ignition (LOI) tests, X-ray fluorescence (XRF), and Fourier-transform infrared (FTIR) spectroscopy. Results: Particle size distribution in raw seawater (EC = 55 000 µs/cm, turbidity = 11 NTU) was 66.4% smaller than 1 µ and 28.3% between 1 to 1.9 µm. Physical damages were not seen on the membranes but telescopic damages were observed which was due to membrane fouling. Removal efficiencies of turbidity and silt density index (SDI) were 84% and 18%, respectively. Membrane oxidation was also seen. Most of the sediments compositions on the membranes were SiO2 , Al2 O3 , MgO, and Fe2 O3 . Biological fouling was detected on the membranes surface. Conclusion: Inaccurate use of chlorine neutralizer caused the residual chlorine to be present in the membrane entering water, which damaged the membrane. Accumulation of clogging agents on membrane surface showed malfunction of pretreatment function, therefore, revision of design and operation of units is necessary. Biological fouling is due to non-effective pre-chlorination of drinking water. Metallic compounds sedimentation on the membrane is due to improper use of anti-fouling chemicals. High SDI in the influent shows the need to change the cartridge filters.

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Abushaban, Almotasembellah, Sergio G. Salinas-Rodriguez, Delia Pastorelli, Jan C. Schippers, Subhanjan Mondal, Said Goueli, and Maria D. Kennedy. "Assessing Pretreatment Effectiveness for Particulate, Organic and Biological Fouling in a Full-Scale SWRO Desalination Plant." Membranes 11, no. 3 (February 27, 2021): 167. http://dx.doi.org/10.3390/membranes11030167.

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In this study, the removal of particulate, organic and biological fouling potential was investigated in the two-stage dual media filtration (DMF) pretreatment of a full-scale seawater reverse osmosis (SWRO) desalination plant. Moreover, the removal of fouling potential in two-stage DMF (DMF pretreatment) was compared with the removal in two-stage DMF installed after dissolved air floatation (DAF) (DAF-DMF pretreatment). For this purpose, the silt density index (SDI), modified fouling index (MFI), bacterial growth potential (BGP), organic fractions and microbial adenosine triphosphate (ATP) were monitored in the pretreatment processes of two full-scale SWRO plants. Particulate fouling potential was well controlled through the two stages of DMF with significant removal of SDI15 (>80%), MFI0.45 (94%) and microbial ATP (>95%). However, lower removal of biological/organic fouling potential (24–41%) was observed due to frequent chlorination (weekly) of the pretreatment, resulting in low biological activity in the DMFs. Therefore, neutralizing chlorine before media filtration is advised, rather than after, as is the current practice in many full-scale SWRO plants. Comparing overall removal in the DAF-DMF pretreatment to that of the DMF pretreatment showed that DAF improved the removal of biological/organic fouling potential, in which the removal of BGP and biopolymers increased by 40% and 16%, respectively. Overall, monitoring ATP and BGP during the pretreatment processes, particularly in DMF, would be beneficial to enhance biological degradation and lower biofouling potential in SWRO feed water.

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Alagha, Omar, and Osama Abuhajar. "Numerical Modeling of Beach Well Intake as Pre-Treatment for a Desalination Plant." Water 12, no. 9 (August 28, 2020): 2420. http://dx.doi.org/10.3390/w12092420.

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Pre-treatment of seawater plays a critical role in removing colloidal particles, algae, sediment, and microbes, which could adversely affect the desalination process. This study focused on the utilization of the natural process of infiltration by beach wells to pre-treat the intake water for the desalination process. The scope of the study was achieved by drilling two beach wells at Al-Khobar and Jubail sites at the Arabian Gulf of Saudi Arabia at 50 m depth each. In addition to that, a total of eight monitoring wells were drilled for pump testing. Numerical modeling was conducted using SEEP/W to investigate the properties of well water flux at the beach wells. The comprehensive physio-chemical parameters such as cation, silt density index (SDI), total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), total organic carbon (TOC), salinity, and alkalinity were analyzed for a quality assessment concerning the actual seawater. Preliminary experimental results show a reduction of the targeted parameters and indicate that beach well sand filtration in the Eastern Province would be a valuable pre-filtration step in reverse osmosis (RO)-based drinking water production systems. The water flux values for both sites were 0.0197 and 0.0208 m3/s/m2, respectively, which corresponds to 72 m3/h/m2 and 1356.48 m3/h/m2. In terms of the rate of pumping flow, the model suggests production can be increased by 20 and 53 times the measured production of the Jubail and Al-Khobar sites, respectively. The experimental results of water parameters, such as cation, SDI, TDS, TSS, etc., indicate that beach well sand filtration in the Eastern Province would be a valuable pre-filtration step in reverse osmosis drinking water production systems.

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Woodall, C. W., C. E. Fiedler, and K. S. Milner. "Stand density index in uneven-aged ponderosa pine stands." Canadian Journal of Forest Research 33, no. 1 (January 1, 2003): 96–100. http://dx.doi.org/10.1139/x02-168.

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Stand density index (SDI) was developed to quantify relative stand density in even-aged stands. Application of SDI in uneven-aged stands has been described mathematically but not justified biologically. Diameter-class trends in SDI and sapwood area across 14 uneven-aged ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) stands in eastern Montana were examined to elucidate the biological underpinnings of the SDI summation method. Results indicate that the SDI summation method is biased in its apportionment of relative stand density across diameter classes in uneven-aged ponderosa pine stands. SDI apportions greater relative density to small trees than to larger ones. Therefore, SDI may overpredict site occupancy for reverse J-shaped diameter distributions with more small trees than large ones, and it may underpredict occupancy with nonreverse J-shaped diameter distributions. Application of the SDI summation method in uneven-aged ponderosa pine stands may be biologically justified only if site occupancy diameter-class trends are taken into account when interpreting SDI values. Replacing the self-thinning scaling factor of the SDI summation method with more biologically relevant scaling relationships may create improved relative density measures for uneven-aged stands.

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Williams, Roger A. "Use of Stand Density Index as an Alternative to Stocking Percent in Upland Hardwoods." Northern Journal of Applied Forestry 20, no. 3 (September 1, 2003): 137–42. http://dx.doi.org/10.1093/njaf/20.3.137.

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Abstract Stand Density Index (SDI) equations were developed and presented for upland hardwoods in southern Ohio. The relationship between SDI and stocking percent from upland hardwood stocking charts were developed, and a diagram displaying this relationship is presented. Critical stand density boundaries equivalent to stocking percent on stocking charts were defined: (1) the C-level of stocking (SDI < 125), (2) the B-level of stocking (125 ≤ SDI < 215), and (3) the A-level of stocking (215 ≤ SDI < 250). A fourth boundary—the region where competition-induced mortality begins—was determined through empirical evidence at an SDI = 175, or 81% stocking. How these boundaries can be utilized in various management strategies is presented. North. J. Appl. For. 20(3):137–142.

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Possato, Ernani Lopes, Natalino Calegario, Gilciano Saraiva Nogueira, Elliezer de Almeida Melo, and Joyce de Almeida Alves. "ESTIMATE OF STAND DENSITY INDEX FOR EUCALYPTUS UROPHYLLA USING DIFFERENT FIT METHODS." Revista Árvore 40, no. 5 (October 2016): 921–29. http://dx.doi.org/10.1590/0100-67622016000500016.

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ABSTRACT The Reineke stand density index (SDI) was created on 1933 and remains as target of researches due to its importance on helping decision making regarding the management of population density. Part of such works is focused on the manner by which plots were selected and methods for the fit of Reineke model parameters in order to improve the definition of SDI value for the genetic material evaluated. The present study aimed to estimate the SDI value for Eucalyptus urophylla using the Reineke model fitted by the method of linear regression (LR) and stochastic frontier analysis (SFA). The database containing pairs of data number of stems per hectare (N) and mean quadratic diameter (Dq) was selected in three intensities, containing the 8, 30 and 43 plots of greatest density, and models were fitted by LR and SFA on each selected intensities. The intensity of data selection altered slightly the estimates of parameters and SDI when comparing the fits of each method. On the other hand, the adjust method influenced the mean estimated values of slope and SDI, which corresponded to -1.863 and 740 for LR and -1.582 and 810 for SFA.

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Kremen, Seymour S., and Matt Tanner. "Silt density indices (SDI), percent plugging factor (%PF): their relation to actual foulant deposition." Desalination 119, no. 1-3 (September 1998): 259–62. http://dx.doi.org/10.1016/s0011-9164(98)00167-2.

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Williams, Roger A. "Stand Density Index for Loblolly Pine Plantations in North Louisiana." Southern Journal of Applied Forestry 20, no. 2 (May 1, 1996): 110–13. http://dx.doi.org/10.1093/sjaf/20.2.110.

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Abstract Stand Density Index (SDI) equations and diagrams were developed and presented for loblolly pine (Pinus taeda L.) plantations in north Louisiana. Two different SDI diagrams are presented—one that utilizes the number of trees per acre and average stand diameter, and a second that uses the number of trees per acre and the basal (ft²) per acre. Basal area is presented as a second alternative to average stand diameter since many practicing foresters commonly use basal area for density management. South. J. Appl. For. 20(2):110-113.

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Zhang, Xiongqing, Quang V. Cao, Lele Lu, Hanchen Wang, Aiguo Duan, and Jianguo Zhang. "Use of Modified Reineke’s Stand Density Index in Predicting Growth and Survival of Chinese Fir Plantations." Forest Science 65, no. 6 (June 10, 2019): 776–83. http://dx.doi.org/10.1093/forsci/fxz033.

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Abstract Stand density index (SDI) has played an important role in controlling stand stocking and modeling stand development in forest stands. Reineke’s SDI (SDI_R) is based on a constant slope of –1.605 for the self-thinning line. For Chinese fir plantations, however, it has been reported that the self-thinning slope varied with site and climate, rendering SDI_R questionable. Remeasured data from 48 plots distributed in Fujian, Jiangxi, Guangxi, and Sichuan provinces were used to develop models for prediction of stand survival and basal area, with SDI_R incorporated as a predictor variable. Also included in the evaluation were growth models based on self-thinning slopes estimated from two groups of sites (SDI_S) or from climate variables (SDI_C). Results indicated that models with climate-sensitive SDI (SDI_C) performed best, followed by SDI_S and SDI_R. The control models without SDI received the worst overall rank. Inclusion of climate-sensitive SDI in growth and survival models can therefore facilitate modeling of the relation between stand density and growth/survival under future climate-change conditions.

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Wang, Liang, Ying Chun Li, He Zhao, Zhao Hui Zhang, Bin Zhao, Hong Wei Zhang, and Ling Xue Cui. "Pretreatment Process of Nanofiltration for Silting Density Index Reduction in Drinking Water Treatment System." Advanced Materials Research 777 (September 2013): 467–71. http://dx.doi.org/10.4028/www.scientific.net/amr.777.467.

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Calcium ions, magnesium ions, and silicate were the main reasons for the high silting density index (SDI) of natural waters. Therefore, they posed serious membrane fouling problems in the nanofiltration (NF) system, which restricted the wide application of this excellent drinking water treatment technology. In this study, the sand filtration and the micro-flocculation/sand filtration hybrid process were investigated as the pretreatment process of NF for SDI reduction. Compared with the sand filtration, the hybrid process of micro-flocculation/sand filtration was more effective for SDI reduction. When polyaluminium chloride (PAC) was used as the flocculant at a dose of 10 mg/L and the filtration rate of the sand filter was controlled at 10 m/h, the SDI value in the effluent of the pretreatment process maintained below 3. As a result, the subsequent NF system stably ran for one year. 68% CODMn was removal by NF. The membrane fouling during the operation was quite slight as the transmembrane pressure (TMP) increased by 17% after one-year use. Chemical cleaning with sodium tripolyphosphate (2%) and sodium dodecyl benzene sulfonate (0.25%) at 6 months interval could effectively recover the flux loss of the NF membrane.

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Innes, J. C., M. J. Ducey, J. H. Gove, W. B. Leak, and J. P. Barrett. "Sizedensity metrics, leaf area, and productivity in eastern white pine." Canadian Journal of Forest Research 35, no. 10 (October 1, 2005): 2469–78. http://dx.doi.org/10.1139/x05-174.

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Sizedensity metrics are used extensively for silvicultural planning; however, they operate on biological assumptions that remain relatively untested. Using data from 12 even-aged stands of eastern white pine (Pinus strobus L.) growing in southern New Hampshire, we compared size-density metrics with stand productivity and its biological components, including leaf area index (LAI) and measures of crown morphology. Density indices included Reineke's stand density index (SDI), a 3/2 relative density law, and trees per hectare. We examined models with and without site index and stand age as components, to predict total stand accretion (PAI), LAI, and growth efficiency (GE). LAI was a strong linear predictor of PAI (R2 = 0.89). However, of the indices tested only SDI was a significant predictor of accretion, and none were significantly related to LAI or GE. Site index was not a significant predictor of any variable when used alone, but in combination with SDI and stand age did lead to significant relationships with PAI (R2 = 0.84), LAI (R2 = 0.67), and GE (R2 = 0.92). Of the density indices tested only trees per hectare was strongly correlated with crown attributes. These results demonstrate that size-density metrics combined with other stand attributes are reasonably correlated with biological measures of stand growth.

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Alhadidi, A., B. Blankert, A. J. B. Kemperman, R. Schurer, J. C. Schippers, M. Wessling, and W. G. J. van der Meer. "Limitations, improvements and alternatives of the silt density index." Desalination and Water Treatment 51, no. 4-6 (January 2013): 1104–13. http://dx.doi.org/10.1080/19443994.2012.705049.

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Zhang, Yang, Pedro N. Carvalho, Tao Lv, Carlos Arias, Hans Brix, and Zhanghe Chen. "Microbial density and diversity in constructed wetland systems and the relation to pollutant removal efficiency." Water Science and Technology 73, no. 3 (October 21, 2015): 679–86. http://dx.doi.org/10.2166/wst.2015.542.

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Microbes are believed to be at the core of the wastewater treatment processes in constructed wetlands (CWs). The aim of this study was to assess the microbial biomass carbon (MBC) and Shannon's diversity index (SDI) in the substrate of CWs planted with Phragmites australis, Hymenocallis littoralis, Canna indica and Cyperus flabelliformis, and to relate MBC and SDI to the pollutant removal in the systems. Significant higher MBC was observed in CWs with H. littoralis and C. indica than in CWs with P. australis, and the MBC differed with season and substrate depth. The microbial community in the wetlands included four phyla: Cyanobacteria, Proteobacteria, Chloroflexi, and Acidobacteria, with a more diverse community structure in wetlands with C. flabelliformis. The MBC in the substrate and the SDI of the 15–20 cm depth correlated with the removal of biochemical oxygen demand, NH4-N and NO3-N. Our results indicate that substrate SDI and MBC can both be regarded as bioindicators of the pollutant removal ability in CWs.

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Alhadidi, A., A. J. B. Kemperman, J. C. Schippers, M. Wessling, and W. G. J. van der Meer. "The influence of membrane properties on the Silt Density Index." Journal of Membrane Science 384, no. 1-2 (November 2011): 205–18. http://dx.doi.org/10.1016/j.memsci.2011.09.028.

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Cha, Donghoon, Heekyung Park, Suhan Kim, Jae-Lim Lim, Sukhyung Kang, and Chung-Hwan Kim. "A statistical approach to analyze factors affecting silt density index." Desalination and Water Treatment 45, no. 1-3 (July 2012): 276–83. http://dx.doi.org/10.1080/19443994.2012.692040.

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Wulandono, Okta, Ernan Rustiadi, and Muhammad Ardiansyah. "Spatial Interaction Based on Sub-District Development Index in Pandeglang Regency." Economics Development Analysis Journal 10, no. 1 (February 9, 2021): 1–11. http://dx.doi.org/10.15294/edaj.v10i1.40708.

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Population movement is a form of spatial interaction between regions. This phenomenon arises asa logical consequence of the heterogeneity of regional development that occurs. PandeglangRegency as an underdeveloped area should not be left behind because of the many leaks of spatialinteractions that are more directed outside this district. Investigating the daily mobilization of thepopulation internally is important in determining which sub-districts play a role as a destination foreconomic activity. The basic data used include the survey origin destination of Banten Province in2019 and data on Potential Villages (Podes) 2019 in the Pandeglang Regency. The method used isthe Scalogram method to determine the Sub-District Development Index (SDI) and the gravitymethod to analyze spatial interactions. The Hierarchical classification was carried out on the SDIvariable, the number of daily movements (density), and the distance between districts. This is doneto see the intensity of the daily movement of the population according to density, distance, andSDI hierarchy class. The spatial interaction magnitude is estimated based on the populationestimation parameters and SDI through the natural logarithmic transformation (ln) of the gravitymethod formula. The results show that the highest average population movement occurs in thehigh-density hierarchy leading to the sub-districts of the SDI 1 hierarchy. The sub-districts ofCadasari, Munjul, Patia, Saketi, and Sukaresmi as sub-districts from which spatial interactionoriginate will produce positive intensity values when compared to other sub-districts. CadasariSub-District will provide a positive spatial interaction value when it becomes the goal of the dailymovement of the population.

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CULLEN, NICOLAS J., BRIAN ANDERSON, PASCAL SIRGUEY, DOROTHEA STUMM, ANDREW MACKINTOSH, JONATHAN P. CONWAY, HUW J. HORGAN, RUZICA DADIC, SEAN J. FITZSIMONS, and ANDREW LORREY. "An 11-year record of mass balance of Brewster Glacier, New Zealand, determined using a geostatistical approach." Journal of Glaciology 63, no. 238 (December 1, 2016): 199–217. http://dx.doi.org/10.1017/jog.2016.128.

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ABSTRACTRecognising the scarcity of glacier mass-balance data in the Southern Hemisphere, a mass-balance measurement programme was started at Brewster Glacier in the Southern Alps of New Zealand in 2004. Evolution of the measurement regime over the 11 years of data recorded means there are differences in the spatial density of data obtained. To ensure the temporal integrity of the dataset a new geostatistical approach is developed to calculate mass balance. Spatial co-variance between elevation and snow depth allows a digital elevation model to be used in a co-kriging approach to develop a snow depth index (SDI). By capturing the observed spatial variability in snow depth, the SDI is a more reliable predictor than elevation and is used to adjust each year of measurements consistently despite variability in sampling spatial density. The SDI also resolves the spatial structure of summer balance better than elevation. Co-kriging is used again to spatially interpolate a derived mean summer balance index using SDI as a co-variate, which yields a spatial predictor for summer balance. The average glacier-wide surface winter, summer and annual balances over the period 2005–15 are 2484, −2586 and −102 mm w.e., respectively, with changes in summer balance explaining most of the variability in annual balance.

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Zhang, Jianwei, Martin W. Ritchie, Douglas A. Maguire, and William W. Oliver. "Thinning ponderosa pine (Pinus ponderosa) stands reduces mortality while maintaining stand productivity." Canadian Journal of Forest Research 43, no. 4 (April 2013): 311–20. http://dx.doi.org/10.1139/cjfr-2012-0411.

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We analyzed 45 years of data collected from three ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) levels-of-growing-stock installations in Oregon (OR) and northern California (CA), USA, to determine the effect of stand density regimes on stand productivity and mortality. We found that periodic annual increment (PAI) of diameter, basal area (BA), volume, and aboveground dry mass were significantly related to stand density index (SDI) and stand age at start of the period; the quadratic trends varied among sites. Precipitation departure from the normal for each period explained a significant amount of residual variation in all PAI variables except diameter. BA production did not change significantly as SDI exceeded 270 trees·ha−1 at the OR sites and 320 trees·ha−1 at the CA site. Stand productivity was the highest at Elliot Ranch (CA) and the least at Blue Mountains (OR). A similar trend held in growth efficiency under lower stand densities (SDI < 600). Most of the mortality was caused by Dendroctonus bark beetles in stands that exceeded SDI of 500 trees·ha−1. Limiting SDI was about 900 trees·ha−1, although plots at Elliot Ranch reached much higher than that. The results demonstrate that silvicultural control of stand density can be a powerful tool for reducing bark beetle caused mortality without sacrificing stand productivity.

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Ahmed, Ahmed, Yvan Gariepy, and Vijaya Raghavan. "Influence of wood-derived biochar on the compactibility and strength of silt loam soil." International Agrophysics 31, no. 2 (April 25, 2017): 149–55. http://dx.doi.org/10.1515/intag-2016-0044.

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Abstract Biochar is proven to enhance soil fertility and increase crop productivity. Given that the influence of biochar on soil compaction remains unclear, selected physico-mechanical properties of soil amended with wood-derived biochar were assessed. For unamended silt loam, the bulk density, maximum bulk density, optimum moisture content, plastic limit, liquid limit, and plasticity index were 1.05 Mg m-3, 1.69 Mg m-3, 16.55, 17.1, 29.3, and 12.2%, respectively. The penetration resistance and shear strength of the unamended silt loam compacted in the standard compaction Proctor mold and at its optimum moisture content were 1800 kPa and 850 kPa, respectively. Results from amending the silt loam with 10% particle size ranges (0.5-212 μm) led to relative decreases of 18.1, 17.75, 66.66, and 97.4% in bulk density, maximum bulk density, penetration resistance, and shear strength, respectively; a 26.8% relative increase in optimum moisture content; along with absolute increases in plastic limit, liquid limit, and plasticity index of 5.3, 13.7, and 8.4%, respectively. While the biochar-amended silt loam soil was more susceptible to compaction, however, soil mechanical impedance enhanced.

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Pizarro, Alonso, Silvano F. Dal Sasso, Matthew T. Perks, and Salvatore Manfreda. "Identifying the optimal spatial distribution of tracers for optical sensing of stream surface flow." Hydrology and Earth System Sciences 24, no. 11 (November 9, 2020): 5173–85. http://dx.doi.org/10.5194/hess-24-5173-2020.

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Abstract. River monitoring is of particular interest as a society that faces increasingly complex water management issues. Emerging technologies have contributed to opening new avenues for improving our monitoring capabilities but have also generated new challenges for the harmonised use of devices and algorithms. In this context, optical-sensing techniques for stream surface flow velocities are strongly influenced by tracer characteristics such as seeding density and their spatial distribution. Therefore, a principal research goal is the identification of how these properties affect the accuracy of such methods. To this aim, numerical simulations were performed to consider different levels of tracer clustering, particle colour (in terms of greyscale intensity), seeding density, and background noise. Two widely used image-velocimetry algorithms were adopted: (i) particle-tracking velocimetry (PTV) and (ii) particle image velocimetry (PIV). A descriptor of the seeding characteristics (based on seeding density and tracer clustering) was introduced based on a newly developed metric called the Seeding Distribution Index (SDI). This index can be approximated and used in practice as SDI=ν0.1/ρρcν1, where ν, ρ, and ρcν1 are the spatial-clustering level, the seeding density, and the reference seeding density at ν=1, respectively. A reduction in image-velocimetry errors was systematically observed for lower values of the SDI; therefore, the optimal frame window (i.e. a subset of the video image sequence) was defined as the one that minimises the SDI. In addition to numerical analyses, a field case study on the Basento river (located in southern Italy) was considered as a proof of concept of the proposed framework. Field results corroborated numerical findings, and error reductions of about 15.9 % and 16.1 % were calculated – using PTV and PIV, respectively – by employing the optimal frame window.

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Ducey, Mark J. "The Ratio of Additive and Traditional Stand Density Indices." Western Journal of Applied Forestry 24, no. 1 (January 1, 2009): 5–10. http://dx.doi.org/10.1093/wjaf/24.1.5.

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Abstract The ratio between additive and original versions of Reineke's stand density index (SDI) has been used as a descriptor of stand structural complexity. That ratio also can be informative for designing efficient sampling methods and for the design of silvicultural experiments. Previous analyses of this ratio have assumed a diameter distribution without truncation, such that trees from zero to infinite dbh are possible. Truncation of the diameter distribution, e.g., by tallying only trees larger than some minimum dbh, moves the ratio much closer to one when the stand has a classic balanced uneven-aged structure. Minimum values of the ratio are found not with classic reverse-J distributions, but with sharply bimodal distributions that might be typical of a two-cohort stand. The implications for the use of novel sampling methods and for experimental designs to test whether the additive or original SDI provides better prediction in irregular stands are discussed.

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Okunev, Igor, and Mariya Tislenko. "SPATIAL DEPENDENCE INDEX: METHODOLOGY FOR MEASURING THE NEIGHBORHOOD EFFECT IN SOCIAL SCIENCE." Вестник Пермского университета. Политология 14, no. 3 (2020): 82–95. http://dx.doi.org/10.17072/2218-1067-2020-3-82-95.

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This article presents the results of the development and application of improved methodological tools based on spatial econometrics. The authors started with analyzing the spatial distribution of two social phenomena – democratization and suicide level. The following procedures were carried out for each indicator: a selection of reliable and regularly collected and published data, density-measuring zoning on the basis of a diagram and a map of extent, calculation of local indicators of spatial autocorrelation (LISA) and calculation of the authors' proposed spatial dependence index (SDI) to identify and interpret anomalous SDI values. The authors obtained anomalous values indicating the supposedly significant role of geographical factors (SDI >0.08): press freedom, political rights protection and state fragility for political regimes; autonomy index and religiousness level for suicides per 100,000 population. The research results are not intended to be exhaustive; however, the authors conclude that spatial econometrics tools, being extrapolated and used along with other traditional methods of political and social sciences, are useful for finding outputs of spatial relations and distribution of certain socio-economic and political phenomena that are not always logically obvious. In addition, the proposed analysis algorithm can be used for the analysis of other quantifiable and statistically tracked phenomena.

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Zhang, Zhen Ying, Da Zhi Wu, and Cha Wang. "Study on the Compressibility of the Silt in Hangzhou, China." Applied Mechanics and Materials 419 (October 2013): 853–57. http://dx.doi.org/10.4028/www.scientific.net/amm.419.853.

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To investigate the compressibility of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the compression coefficient varies from 0.06 to 0.40MPa-1, and the compression index varies from 0.015 to 0.108. Finally, the properties of the compression are studied, and find that the compressibility of the silt soil is very large, and the relationship between the initial void ratio and the logarithm pressure is linear.

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Alhadidi, A., A. J. B. Kemperman, B. Blankert, J. C. Schippers, M. Wessling, and W. G. J. van der Meer. "Silt Density Index and Modified Fouling Index relation, and effect of pressure, temperature and membrane resistance." Desalination 273, no. 1 (June 2011): 48–56. http://dx.doi.org/10.1016/j.desal.2010.11.031.

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Godoy, Maria M., Guillermo E. Defossé, Lucas O. Bianchi, Miguel M. Davel, and Tomás E. Withington. "Fire-caused tree mortality in thinned Douglas-fir stands in Patagonia, Argentina." International Journal of Wildland Fire 22, no. 6 (2013): 810. http://dx.doi.org/10.1071/wf12107.

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In 2003 in a municipal park near Esquel, Patagonia, Argentina, plots within a 21-year-old Douglas-fir (Pseudotsuga menziesii) afforested area were subjected to three silvicultural treatments (thinning to Reineke’s Stand Density Index (SDI) of 900, 700, 500). In March 2007 all plots were burned by a wildfire that presented extreme fire behaviour. Three weeks after the wildfire we assessed mortality, height of scorch and percentage of crown scorch, and during three subsequent growing seasons we measured mortality and growth parameters. At the end of the study, mortality differed significantly among treatments and an untreated control, and ranged from 100% in the untreated control to 25, 10 and 5% in the SDI 900, 700 and 500 treatments. The highest growth parameters and lower mortality rates were achieved at SDI indices of 700 or 500 (i.e. in the least dense plots). Trees thinned to these densities not only appear to withstand extreme fires, at least under the conditions presented, but also to achieve the highest growth rates.

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Guo, Zhibin, and Xiaolin Du. "Study on The Relationship Between Silt Density Index and Turbidity in Wastewater Membrane Treatment." IOP Conference Series: Earth and Environmental Science 687, no. 1 (March 1, 2021): 012006. http://dx.doi.org/10.1088/1755-1315/687/1/012006.

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Wang, Liyan, Bin Zhang, Hongmei Xie, Wenwei Ji, and Xiang Huang. "Study on Shear Strength Characteristics of Marine Silt Modified by Steel Slag." Advances in Civil Engineering 2021 (August 18, 2021): 1–15. http://dx.doi.org/10.1155/2021/9647977.

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Modern coastal cities continue to expand to the sea, but the marine silt foundation has high water content and poor bearing capacity. Therefore, it is necessary to find economical and rapid ways to reduce the water content of the silt and improve the bearing capacity of the silt foundation. The steel slag is considered to be incorporated into silt to effectively reduce the moisture content of soil and improve the bearing capacity of the foundation due to its hard texture and strong water absorption capacity. In this paper, the shear strength characteristics of marine silt modified by steel slag were studied using an automatic triaxial instrument, as well as the relationship between steel slag incorporation and modified silt density. Experimental results showed that the incorporation of steel slag can effectively improve the shear strength of the silt. Besides, the influences of water content, steel slag incorporation, and confining pressure on the stress-strain curve characteristics and failure deviatoric stress of modified silt were also analyzed. The addition of steel slag increases the failure deviatoric stress of the silt. However, the increase of water content will weaken the effect of steel slag incorporation. The shear strength index of improved silt with different steel slag incorporation was compared with that of traditional soil, verifying the feasibility of its application in engineering construction.

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Pocovi-Gerardino, Gabriela, Maria Correa-Rodríguez, José-Luis Callejas Rubio, Raquel Ríos Fernández, María Martín Amada, María-Gracia Cruz Caparros, Blanca Rueda-Medina, and Norberto Ortego-Centeno. "The Relationships of High-Sensitivity C-Reactive Protein and Homocysteine Levels With Disease Activity, Damage Accrual, and Cardiovascular Risk in Systemic Lupus Erythematosus." Biological Research For Nursing 22, no. 2 (November 25, 2019): 169–77. http://dx.doi.org/10.1177/1099800419889192.

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Chronic inflammation coupled with cardiovascular disease (CVD) risk factors influences the progression of atherosclerosis in systemic lupus erythematosus (SLE). High-sensitivity C-reactive protein (hs-CRP) and homocysteine (Hcy) are associated with the risk of CVD in the general population, but their associations with CV risk and disease activity in SLE are unclear. In this cross-sectional study ( N = 139 SLE patients, mean age = 45.27 ± 13.18 years), we investigated associations between hs-CRP and Hcy levels and disease activity, damage accrual, and CVD risk in SLE. Disease activity and damage accrual were measured with the SLE Activity Index 2000 (SLEDAI-2K), the Systemic Lupus Erythematosus International Collaborating Clinics Group/American College of Rheumatology damage index (SDI), and anti-double-stranded DNA antibodies (anti-dsDNA). CVD risk factors of obesity, diabetes mellitus, hypertension, blood lipids, and ankle–brachial index were collected. Linear regression analysis and one-way analysis of variance were used to analyze relationships of hs-CRP and Hcy with SLE activity, damage accrual, and CVD risk factors. Results: hs-CRP correlated significantly with SLEDAI-2K ( p = .036), SDI ( p = .00), anti-dsDNA titers ( p = .034), diabetes ( p = .005), and obesity ( p = .027). hs-CRP and Hcy correlated with triglyceride (TG) levels ( p = .032 and p < .001, respectively), TG/high-density lipoprotein cholesterol index ( p = .020 and p = .001, respectively), and atherogenic index of plasma ( p = .006 and p = .016, respectively). hs-CRP levels >3 mg/L correlated with SDI score ( p = .012) and several CVD risk factors. Discussion: Findings suggest SLE patients with elevated hs-CRP and/or Hcy have a higher prevalence of CVD risk factors.

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Correa Rodríguez, M., G. Pocovi-Gerardino, J. L. Callejas-Rubio, R. Ríos Fernández, S. Delolmo-Romero, N. Ortego, and B. Rueda-Medina. "AB0315 DISEASE DAMAGE ACCRUAL AND LOW BONE MINERAL DENSITY IN FEMALE PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS." Annals of the Rheumatic Diseases 80, Suppl 1 (May 19, 2021): 1182.3–1183. http://dx.doi.org/10.1136/annrheumdis-2021-eular.2011.

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Background:Osteoporosis is a common comorbidity in patients with systemic lupus erythematosus (SLE). Available evidence showed that autoimmunity and associated inflammation play main effect in the pathogenesis of negative skeletal effects in SLE patients. However, the potential contribution of disease-associated factors to bone status in SLE is not well known since the reported risk factors from different studies differ greatly.Objectives:The aim of this study was to examine frequency of reduced bone mass in SLE women, and determine their potential associations with disease activity, damage accrual and SLE-related clinical markers.Methods:A cross-sectional study including a total 121 Caucasian pre-menopausal and postmenopausal women was conducted (mean age 49.29±12.43 years). The SLE Disease Activity Index (SLEDAI-2K) and the SDI Damage Index were used to asses disease activity and disease-related damage, respectively. Bone mineral density (BMD) of the left femoral neck and lumbar spine (L2–L4) were measured by dual-energy X-ray absorptiometry (Hologic QDR 400).Results:Ten patients (8.3%) had osteoporosis, 63 (52.1%) patients had osteopenia and 6.8% of women had history of previous fracture. Patients with low bone mass had a significantly higher mean SDI (1.36±1.26 versus 0.70±1.09 p=0.003). T-score at lumbar spine was inversely correlated with SDI score (r=-0.222, p=0.014) and complement C3 level (r=-0.206, p=0.024). Results of bivariate correlations showed that T-score at lumbar spine was inversely correlated with SDI score (r=-0.222, p=0.014) and complement C3 level (r=-0.206, p=0.024). SDI scores were significantly different between patients with osteoporosis, osteopenia and normal BMD after adjusting for age, menstrual status, BMI, time since diagnosis and corticoid use (p=0.004).Conclusion:There is a high prevalence of low BMD in Caucasian women with SLE and this status of osteopenia/osteoporosis was associated with higher damage accrual scores, supporting that disease damage may itself be a major contributor to the low BMD. SLE women with organ damage require regular bone status monitoring to prevent further musculoskeletal damage. Since diminished BMD is a main comorbidity it is therefore essential to study, monitor and prevent osteoporosis in SLE women to avoid fractures leading to reduced quality of life.References:[1]Wang X, Yan S, Liu C, Xu Y, Wan L, Wang Y, et al. Fracture risk and bone mineral density levels in patients with systemic lupus erythematosus: a systematic review and meta-analysis. Osteoporos Int 2016;27:1413–23.[2]Mendoza-Pinto C, Rojas-Villarraga A, Molano-Gonzalez N, Jimenez-Herrera EA, De La Luz Leon-Vazquez M, Montiel-Jarquõn A, et al. Bone mineral density and vertebral fractures in patients with systemic lupus erythematosus: A systematic review and meta-regression. PLoS One 2018;13:1–15.[3]Xia J, Luo R, Guo S, Yang Y, Ge S, Xu G, et al. Prevalence and Risk Factors of Reduced Bone Mineral Density in Systemic Lupus Erythematosus Patients: A Meta-Analysis. Biomed Res Int 2019;2019.[4]Carli L, Tani C, Spera V, Vagelli R, Vagnani S, Mazzantini M, et al. Risk factors for osteoporosis and fragility fractures in patients with systemic lupus erythematosus. Lupus Sci Med 2016;3:1–5.Acknowledgements:This research was supported by the grant PI0523-2016 from “Consejería de igualdad, salud y políticas sociales” (Junta de Andalucía) and is part of the research group LyDIMED “Lupus y Dieta Mediterránea”.Disclosure of Interests:None declared

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Faizatunnikmah, Salma, Djoko Nugroho, and Waluyo Waluyo. "Comparative Study of Sports Participation Index in Wonogiri Regency in 2017 and 2020." PHEDHERAL 17, no. 2 (May 23, 2021): 29. http://dx.doi.org/10.20961/phduns.v17i2.51457.

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<p><em>This research uses descriptive and comparative research methods. The sampling technique in this study was stratified random sampling with cluster sampling. The samples taken in this study were Wonogiri District as a district with high population density, Slogohimo sub-district as a district with medium population density and Pracimantoro District as a sub-district with low population density and divided into age group and gender, totaling 270 people. The data collection technique in this study was a questionnaire technique. The reliability test in this study is guided by the SDI instrument as an instrument for measuring the results of sports development which has been trusted because it has been patented in the book Sport Development Index 2007 by Cholik and Maksum. The validity test of the measuring instrument used is the standard set in the Sport Development Index (SDI). The data analysis technique in this research is the stage of data collection, data reduction, data presentation, and drawing conclusions. The results of this study are: (1) the sports participation index in Wonogiri Regency is 0.388. The index was obtained by combining the sports participation index in Wonogiri District of 0.588, the sports participation index in Slogohimo District of 0.488, and the participation index of the Pracimantoro District of 0.477. The sports participation index of Wonogiri Regency shows that the level of sports participation is included in the low category, (2) The comparison of sports participation in Wonogiri Regency in 2017 and 2020 is sports participation in 2017 of 0.237 while sports participation in 2020 is 0.388 which means sports participation in Wonogiri Regency 2020 has increased and is better than in 2017, (3) The sports development of Wonogiri Regency in terms of sports participation is still far from being good or advanced, there are many things that need to be considered and addressed by the Wonogiri Regency government.</em></p>

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Zhang, Zhen Ying, Da Zhi Wu, and Cha Wang. "Study on the Shear Strength Properties of the Silt in Hangzhou, China." Applied Mechanics and Materials 405-408 (September 2013): 349–52. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.349.

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To investigate the shear strength properties of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the cohesion force varies from 20.8 to 28.3kPa, and the internal friction angle varies from 12.3 to 31.8degree. Finally, the properties of the shear strength are studied, and find that the relationship between the shear stress and the shear strain is conformity with the strain hardening curve, and the relationship between the shear strength and the vertical pressure applied on the soil samples is linear, and agrees with the Coulombs law.

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TANG, XIAO LIN, TRACY YANER ZHU, VIVIAN W. HUNG, LING QIN, CHUN-KWOK WONG, EMILY W. KUN, LAI SHAN TAM, and EDMUND K. LI. "Increased Organ Damage Associated with Deterioration in Volumetric Bone Density and Bone Microarchitecture in Patients with Systemic Lupus Erythematosus on Longterm Glucocorticoid Therapy." Journal of Rheumatology 39, no. 10 (August 15, 2012): 1955–63. http://dx.doi.org/10.3899/jrheum.120213.

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Objective.To evaluate bone quality in patients with systemic lupus erythematosus (SLE) who were undergoing longterm glucocorticoid (GC) therapy, and to focus on the correlation between bone quality and organ damage.Methods.Seventy-eight female patients with SLE and organ damage taking longterm GC, and 72 age-matched SLE patients without damage taking longterm GC were recruited for study. Clinical variables of interest included disease activity, cumulative organ damage (by Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index; SDI), major organ involvement (musculoskeletal damage and neuropsychiatric damage, etc.), and use of medication. Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry. Bone geometry, volumetric BMD (vBMD), microarchitecture, and biomechanical properties were measured by high-resolution peripheral quantitative computed tomography (HR-pQCT).Results.Patients were mean age of 45 years (SD 10) and 54% were postmenopausal. The median SDI score of the cohort was 1 (interquartile range 1−2, range 1−5). Compared with patients without damage, the prevalence of osteopenia at either total hip or lumbar spine was significantly higher, and there were trends of deterioration of bone geometry, vBMD, microarchitecture, and biomechanical properties in patients with organ damage. Potential risk factors for bone quality in patients with damage were screened by univariate analysis. During multiple regression analysis, SDI was the only clinical variable consistently associated with deterioration of vBMD and microarchitecture.Conclusion.Cumulative organ damage consistently correlated with deterioration of vBMD and bone microarchitecture in SLE patients with damage on longterm GC therapy. HR-pQCT provides an insight into the underlying mechanism of bone loss in SLE.

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Berguson, William E., David F. Grigal, and Peter C. Bates. "Relative stocking index: a proposed index of site quality." Canadian Journal of Forest Research 24, no. 7 (July 1, 1994): 1330–36. http://dx.doi.org/10.1139/x94-173.

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Site index is difficult to implement and interpret in multispecies, multiple-aged stands, and its relationship to site factors is obscure. Using data from the USDA forest inventory and analysis (FIA) for the Lake States, we developed log-log relationships between mean tree size and stand density for five cover types. Fits were good, with r2 from 0.96 to 0.98 and slopes from −0.948 to −0.995. We define an alternative index of site quality, the relative stocking index (RSI), as the ratio of a stand's measured density to that predicted using the log–log relationship for its cover type (the norm). We divided the range of RSI into three classes for each type (<0.9 of norm, >0.91 but <1.1 of norm, and >1.1 of norm). Based on analyses of the 1977 and 1990 FIA data from Minnesota, class assignments for individual stands remained constant over that 13-year period. Relationships between site factors and either RSI classes or analogous classes based on site index were examined in a subset of 169 stands. Temperature, precipitation, silt content of surface soil, and calculated annual water deficit all differed significantly among RSI classes, but not among site-index classes. The RSI is easy to apply, robust (resistant to change), and related to site factors. It merits additional examination as an index of site quality, especially in heterogenous stands.

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Yunus, Budiman, Sharifuddin Bin Andy Omar, and Basse Siang Parawansa. "STUDY OF MANGROVE COMMUNITY STRUCTURE IN UJUNG BATU BEACH WATER, FLORES SEA, JENEPONTO DISTRICT." International Journal of Research -GRANTHAALAYAH 8, no. 5 (May 28, 2020): 108–20. http://dx.doi.org/10.29121/granthaalayah.v8.i5.2020.97.

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This study aims to examine the density, frequency and closure of mangrove areas. In addition, it also analyzed the ecological index (index of diversity, uniformity, and dominance) of mangrove vegetation in the waters of Ujung Batu, Flores Sea, Jeneponto Regency. This research was conducted using the 10 x 10 m2 transect plot method. The data obtained were analyzed to determine the density, frequency, closure and important value index (IVI) as well as to analyze the diversity index, uniformity and dominance index. The results of this study are; mangrove communities in the waters of the Ujung Batu, Flores coast, consists of types Avicennia alba, A. marina, A. officinalis, Sonnneratia alba and Rhizophora stylosa. A. alba dominates at the three observation stations (I, II and III). This is marked by the high importance (IVI) at all levels. The diversity index (H ') at the study site ranged from 0.36 - 0.51, indicating a low level of diversity. The Simpson dominance index (SDI) ranges from 0.34 to 0.54, indicating that one of the species (A. alba) dominates the mangrove area in the study site.

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Hossein Fayaz, Seyed Mohammad, Roya Mafigholami, Fatemeh Razavian, and Karim Ghasemipanah. "Correlations between silt density index, turbidity and oxidation-reduction potential parameters in seawater reverse osmosis desalination." Water Science and Engineering 12, no. 2 (June 2019): 115–20. http://dx.doi.org/10.1016/j.wse.2019.05.006.

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Journal articles on the topic 'Silt Density Index (SDI)'

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