Top 100 scientists can be ranked globally or specific to the following regions including Africa, Asia, Europe, North America, Latin America, Oceania, Arab League, ASEAN, EECA, and BRICS based on total H-index scores without any breakdown by subject areas. Top 100 rankings in the world, in a continent, or a region include standardized subjects areas of Agriculture & Forestry, Arts, Design and Architecture, Business & Management, Economics & Econometrics, Education, Engineering & Technology, History, Philosophy, Theology, Law/Law and Legal Studies, Medical and Health Sciences, Natural Sciences, Social Sciences, Art and Humanities Rankings and Social Sciences and Humanities Rankings BETA VERSION. Subject field ranking in world, region, country and university is beta version since subject field "others" (873,690 scientists profile whose branch cannot be determined, not yet edited or determined) is excluded, so the ranking will change as the others fields are edited. Please note that. Subjects indicated as “ * others ” will not be included in the ranking by regions and subjects.
Estuarine Ecology
Benthos
Ecosystem modelling
Spatial Ecology
Metrics
H-Index
i10 Index
Citation
99
283
33,019
micro/nano plastic pollution and health
eco-epidemiology
mixture toxicity
ecosystem change and
Metrics
H-Index
i10 Index
Citation
74
157
26,715
Morphodynamics
sediment transport
estuaries
tidal inlets
rivers
Metrics
H-Index
i10 Index
Citation
51
169
10,773
Hydrology
Water Resources
Forecasting
Climate Change
Flood risk
Metrics
H-Index
i10 Index
Citation
50
86
12,716
climate adaptation
water management
environmental modelling
climate change
uncertainty
Metrics
H-Index
i10 Index
Citation
47
84
14,749
fluid mechanics
sediment dynamics
cohesive sediment
Metrics
H-Index
i10 Index
Citation
47
121
9,705
Metrics
H-Index
i10 Index
Citation
46
101
9,345
Hydrology
Water Resources
Forecasting
Predictive Uncertainty
Data Assimilation
Metrics
H-Index
i10 Index
Citation
42
102
6,084
River restoration
Fish Ecology
Water Framework Directive
Metrics
H-Index
i10 Index
Citation
39
73
5,721
* Rankings
Ranking Based
On Selection: 10
Coastal Morphology
Hydrodynamics
Sediment Transport
Morphodynamic Forward Modelling
Coastal Engineering
Metrics
H-Index
i10 Index
Citation
37
75
5,596
* Rankings
Ranking Based
On Selection: 11
geochemie
hydrologie
watermanagement
bodemmanagement
Metrics
H-Index
i10 Index
Citation
37
75
4,464
* Rankings
Ranking Based
On Selection: 12
Coastal morphology
Coastal Engineering
Coastal Hazards
Flood Risk
Metrics
H-Index
i10 Index
Citation
36
70
6,232
* Rankings
Ranking Based
On Selection: 13
Coastal Engineering
Coastal Structures
Hydraulic Engineering
Metrics
H-Index
i10 Index
Citation
36
97
5,048
* Rankings
Ranking Based
On Selection: 14
water management
flood risk
landscape ecology
policy analysis
Metrics
H-Index
i10 Index
Citation
35
77
5,590
* Rankings
Ranking Based
On Selection: 15
Water management
Climate adaptation
hydrology
sea level rise
Metrics
H-Index
i10 Index
Citation
35
56
7,831
* Rankings
Ranking Based
On Selection: 16
hydraulics
measuring techniques
asset management
Metrics
H-Index
i10 Index
Citation
34
97
4,273
* Rankings
Ranking Based
On Selection: 17
wetland hydrology
peatlands
carbon dynamics
land subsidence
flood risk management
Metrics
H-Index
i10 Index
Citation
33
52
6,934
* Rankings
Ranking Based
On Selection: 18
River Morphology
Fluvial Morphology
Morphodynamics
Mathematical Modelling
River Engineering
Metrics
H-Index
i10 Index
Citation
33
63
4,087
* Rankings
Ranking Based
On Selection: 19
nature-based coastal defenses
coastal zone management
ecosystem-based adaptation
marshes and mangroves
Metrics
H-Index
i10 Index
Citation
32
47
6,022
* Rankings
Ranking Based
On Selection: 20
hydrogeology
groundwater
freshwater
coastal aquifers
numerical modelling
Metrics
H-Index
i10 Index
Citation
32
81
4,294
* Rankings
Ranking Based
On Selection: 21
soil and groundwater (bio)chemistry
Metrics
H-Index
i10 Index
Citation
32
55
4,050
* Rankings
Ranking Based
On Selection: 22
Fine sediment transport and morphology in fluvial estuarine and marine environments
Metrics
H-Index
i10 Index
Citation
31
59
3,074
* Rankings
Ranking Based
On Selection: 23
geologie
kustprocessen
geomorfologie
Metrics
H-Index
i10 Index
Citation
29
53
2,984
* Rankings
Ranking Based
On Selection: 24
Inversion
Modeling
Hydrogeophysics
Near-surface geophysics
Metrics
H-Index
i10 Index
Citation
28
37
2,478
* Rankings
Ranking Based
On Selection: 25
waterveiligheid
flood risk management
overstromingsrisico's
Metrics
H-Index
i10 Index
Citation
27
51
3,203
* Rankings
Ranking Based
On Selection: 26
environmental assessments
indicators
benthic ecology
eutrophication
science-policy
Metrics
H-Index
i10 Index
Citation
27
36
3,245
* Rankings
Ranking Based
On Selection: 27
Coastal changes
Coastal Morphology
Sandy Beaches
port sedimentation
numerical modelling of coastal morphodynamics
Metrics
H-Index
i10 Index
Citation
26
44
4,531
* Rankings
Ranking Based
On Selection: 28
Environmental chemistry
risk assessment
Metrics
H-Index
i10 Index
Citation
25
35
1,883
* Rankings
Ranking Based
On Selection: 29
ocean wave dynamics
climate and statistics
Metrics
H-Index
i10 Index
Citation
24
49
11,925
* Rankings
Ranking Based
On Selection: 30
Adaptation planning
water management
climate modelling
Metrics
H-Index
i10 Index
Citation
24
30
2,608
* Rankings
Ranking Based
On Selection: 31
geotechnical engineering
geosynthetics
ground improvement
Metrics
H-Index
i10 Index
Citation
23
40
2,714
* Rankings
Ranking Based
On Selection: 32
Flood Risk
Hydrology
Metrics
H-Index
i10 Index
Citation
22
28
1,941
* Rankings
Ranking Based
On Selection: 33
environmental biotechnology
geotechnical engineering
biogeochemistry
Metrics
H-Index
i10 Index
Citation
22
28
6,762
* Rankings
Ranking Based
On Selection: 34
Catchment hydrology
hydrometeorology
climate change
big data
HPC & cloud
Metrics
H-Index
i10 Index
Citation
22
25
1,880
* Rankings
Ranking Based
On Selection: 35
Sediment Transport & Coastal Morphology
Metrics
H-Index
i10 Index
Citation
22
34
1,775
* Rankings
Ranking Based
On Selection: 36
kustmorfologie
waddenzee
estuaria
waddeneilanden
morfodynamiek
Metrics
H-Index
i10 Index
Citation
22
38
2,130
* Rankings
Ranking Based
On Selection: 37
Coastal Engineering
Coastal and River Structures
Coastal Morphology
Metrics
H-Index
i10 Index
Citation
22
33
2,324
* Rankings
Ranking Based
On Selection: 38
Metrics
H-Index
i10 Index
Citation
22
26
2,211
* Rankings
Ranking Based
On Selection: 39
storm surge
waves
coastal hazards
Metrics
H-Index
i10 Index
Citation
21
30
1,536
* Rankings
Ranking Based
On Selection: 40
Ecology
flood risk management
coastal zone management
river basin management
Metrics
H-Index
i10 Index
Citation
21
32
2,837
* Rankings
Ranking Based
On Selection: 41
sea-level change
sedimentology
deltas
geomechanics
quaternary geology
Metrics
H-Index
i10 Index
Citation
20
27
1,958
* Rankings
Ranking Based
On Selection: 42
Oceanography and Limnology
Coastal Dynamics
Water Quality
Ocean Colour Remote Sensing
Optical and Spatial Modelling
Metrics
H-Index
i10 Index
Citation
20
31
1,397
* Rankings
Ranking Based
On Selection: 43
Primary production
eutrophication
modelling
Metrics
H-Index
i10 Index
Citation
20
25
2,311
* Rankings
Ranking Based
On Selection: 44
Metrics
H-Index
i10 Index
Citation
19
28
1,937
* Rankings
Ranking Based
On Selection: 45
hydrology
climate change
Metrics
H-Index
i10 Index
Citation
19
22
2,448
* Rankings
Ranking Based
On Selection: 46
Water management
macrophytes
ecohydraulics
limnology
water quality and ecological modelling
Metrics
H-Index
i10 Index
Citation
19
30
2,037
* Rankings
Ranking Based
On Selection: 47
Hydroinformatics
Earth Observation
Data Assimilation
Artificial Intelligence
Environmental engineering and ecology
Metrics
H-Index
i10 Index
Citation
19
29
1,846
* Rankings
Ranking Based
On Selection: 48
flood risk management
Metrics
H-Index
i10 Index
Citation
19
31
3,269
* Rankings
Ranking Based
On Selection: 49
systemecology
governance
limnology
sustainability
management
Metrics
H-Index
i10 Index
Citation
19
25
1,176
* Rankings
Ranking Based
On Selection: 50
coastal development
eco-engineering
sediment toxicity
Metrics
H-Index
i10 Index
Citation
19
26
1,144
* Rankings
Ranking Based
On Selection: 51
Geotechnical Engineering
Numerical and Constitutive Modeling in Geomechanics
Metrics
H-Index
i10 Index
Citation
18
30
916
* Rankings
Ranking Based
On Selection: 52
hydrologie
waterkwaliteit
landbouw
monitoring
Metrics
H-Index
i10 Index
Citation
18
27
1,791
* Rankings
Ranking Based
On Selection: 53
Metrics
H-Index
i10 Index
Citation
18
27
2,719
* Rankings
Ranking Based
On Selection: 54
Geographic Information Science
Exposure Assessment
Remote Sensing
Metrics
H-Index
i10 Index
Citation
18
18
1,099
* Rankings
Ranking Based
On Selection: 55
risk analysis
flood risk
water supply
drought
robustness
Metrics
H-Index
i10 Index
Citation
18
26
1,500
* Rankings
Ranking Based
On Selection: 56
Fluvial morphology
Metrics
H-Index
i10 Index
Citation
18
37
1,479
* Rankings
Ranking Based
On Selection: 57
hillslope and watershed hydrology
flood forecasting
hydrological modelling
Metrics
H-Index
i10 Index
Citation
17
18
1,351
* Rankings
Ranking Based
On Selection: 58
Metrics
H-Index
i10 Index
Citation
17
22
1,879
* Rankings
Ranking Based
On Selection: 59
environmental microbiology
Metrics
H-Index
i10 Index
Citation
16
18
1,600
* Rankings
Ranking Based
On Selection: 60
earth observations
environmental modeling
software design
visualization
machine learning
Metrics
H-Index
i10 Index
Citation
16
22
2,720
* Rankings
Ranking Based
On Selection: 61
Metrics
H-Index
i10 Index
Citation
16
26
1,001
* Rankings
Ranking Based
On Selection: 62
Geochemie
Metrics
H-Index
i10 Index
Citation
16
16
1,751
* Rankings
Ranking Based
On Selection: 63
soil dynamics
Metrics
H-Index
i10 Index
Citation
16
19
1,095
* Rankings
Ranking Based
On Selection: 64
geotechniek
monitoring
dijken
Metrics
H-Index
i10 Index
Citation
16
22
771
* Rankings
Ranking Based
On Selection: 65
Metrics
H-Index
i10 Index
Citation
16
26
1,277
* Rankings
Ranking Based
On Selection: 66
Foundation engineering
underground construction
soil-structure interaction
forensic engineering
observational method
Metrics
H-Index
i10 Index
Citation
15
23
786
* Rankings
Ranking Based
On Selection: 67
hydrology
groundwater - surface water interaction
pathways
coastal groundwater
Metrics
H-Index
i10 Index
Citation
15
21
1,041
* Rankings
Ranking Based
On Selection: 68
River Dynamics & Engineering
Hydraulics
Fluvial Geomorphology
Sediment Transport
Water Infrastructure
Metrics
H-Index
i10 Index
Citation
15
25
925
* Rankings
Ranking Based
On Selection: 69
scour
erosion
turbulence
grass revetments
piping
Metrics
H-Index
i10 Index
Citation
15
22
1,799
* Rankings
Ranking Based
On Selection: 70
Marine Geology
bedform dynamics
glacial morphology and sedimentology
Metrics
H-Index
i10 Index
Citation
15
20
1,043
* Rankings
Ranking Based
On Selection: 71
Geotechnics
Transportation
Optimization
Metrics
H-Index
i10 Index
Citation
15
19
669
* Rankings
Ranking Based
On Selection: 72
flood risk management
resilience
hydrology
climate-related security risks
Metrics
H-Index
i10 Index
Citation
15
18
728
* Rankings
Ranking Based
On Selection: 73
water management
building with nature
pilot projects
innovation
Metrics
H-Index
i10 Index
Citation
15
17
892
* Rankings
Ranking Based
On Selection: 74
Metrics
H-Index
i10 Index
Citation
14
15
3,166
* Rankings
Ranking Based
On Selection: 75
Coastal hydrodynamics and morphology
Metrics
H-Index
i10 Index
Citation
14
14
1,050
* Rankings
Ranking Based
On Selection: 76
Hydrodynamics
Metrics
H-Index
i10 Index
Citation
14
15
740
* Rankings
Ranking Based
On Selection: 77
Coastal Engineering
Nearshore Processes
coral reefs
coastal zone management
coastal adaptation
Metrics
H-Index
i10 Index
Citation
13
16
417
* Rankings
Ranking Based
On Selection: 78
Coastal Engineering
Coastal Morphology
Morphodynamic Modelling
Sediment Transport
Building with Nature
Metrics
H-Index
i10 Index
Citation
13
15
804
* Rankings
Ranking Based
On Selection: 79
coasts
climate change
sea level rise
deltas
adaptation
Metrics
H-Index
i10 Index
Citation
13
13
744
* Rankings
Ranking Based
On Selection: 80
water quality
sediment quality
Metrics
H-Index
i10 Index
Citation
13
16
1,079
* Rankings
Ranking Based
On Selection: 81
air-water flow
pipe flow
pressure transients
control systems
renewable energy
Metrics
H-Index
i10 Index
Citation
13
16
615
* Rankings
Ranking Based
On Selection: 82
Metrics
H-Index
i10 Index
Citation
13
13
1,230
* Rankings
Ranking Based
On Selection: 83
Geophysics
Geomechanics
Geo-Energy
Hydrogeology
Geomatics
Metrics
H-Index
i10 Index
Citation
13
18
2,802
* Rankings
Ranking Based
On Selection: 84
water management
urban resilience
Metrics
H-Index
i10 Index
Citation
13
14
922
* Rankings
Ranking Based
On Selection: 85
Environmental studies
water quality and transport modelling
Metrics
H-Index
i10 Index
Citation
13
14
646
* Rankings
Ranking Based
On Selection: 86
geotechniek
aardbevingen
verweking
offshore
Metrics
H-Index
i10 Index
Citation
13
14
762
* Rankings
Ranking Based
On Selection: 87
Scenarios
Innovation
Climate Adaptation
Sustainable Development
Water Management
Metrics
H-Index
i10 Index
Citation
13
13
1,563
* Rankings
Ranking Based
On Selection: 88
Metrics
H-Index
i10 Index
Citation
12
12
1,811
* Rankings
Ranking Based
On Selection: 89
Coastal Engineering
Metrics
H-Index
i10 Index
Citation
12
15
717
* Rankings
Ranking Based
On Selection: 90
geotechnical engineering
numerical modelling
soil settlement
material point method
dike stablity
Metrics
H-Index
i10 Index
Citation
12
13
670
* Rankings
Ranking Based
On Selection: 91
governance
delta governance
monitoring
governance arrangementen
implementation
Metrics
H-Index
i10 Index
Citation
12
13
570
* Rankings
Ranking Based
On Selection: 92
soft soil engineering
Metrics
H-Index
i10 Index
Citation
12
13
456
* Rankings
Ranking Based
On Selection: 93
Interoperability
integrated modelling
water management
innovation management
Metrics
H-Index
i10 Index
Citation
12
13
1,104
* Rankings
Ranking Based
On Selection: 94
waterbeheer milieueffect rapportage
Metrics
H-Index
i10 Index
Citation
12
13
951
* Rankings
Ranking Based
On Selection: 95
water management
aquatic ecology
Metrics
H-Index
i10 Index
Citation
12
13
657
* Rankings
Ranking Based
On Selection: 96
water quality modelling monitoring management - Water Framework Directive
Metrics
H-Index
i10 Index
Citation
12
13
528
* Rankings
Ranking Based
On Selection: 97
Morphodynamics
Estuaries & Coasts
Intertidal Flats
Field Measurements
Adaptation Strategies
Metrics
H-Index
i10 Index
Citation
11
13
677
* Rankings
Ranking Based
On Selection: 98
Geotechnical Engineering
Metrics
H-Index
i10 Index
Citation
11
12
591
* Rankings
Ranking Based
On Selection: 99
Flood forecasting and early warning
Flood inundation modelling under uncertainty
Remote sensing
Metrics
H-Index
i10 Index
Citation
11
11
1,220
* Rankings
Ranking Based
On Selection: 100
river morphodynamics
applied mathematics
Metrics
H-Index
i10 Index
Citation
11
11
437
Estuarine Ecology
Benthos
Ecosystem modelling
Spatial Ecology
micro/nano plastic pollution and health
eco-epidemiology
mixture toxicity
ecosystem change and
Morphodynamics
sediment transport
estuaries
tidal inlets
rivers
Hydrology
Water Resources
Forecasting
Climate Change
Flood risk
Marjolijn Haasnoot
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
47
84
14,749
climate adaptation
water management
environmental modelling
climate change
uncertainty
fluid mechanics
sediment dynamics
cohesive sediment
AR (Ap) Van Dongeren
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
46
101
9,345
Hydrology
Water Resources
Forecasting
Predictive Uncertainty
Data Assimilation
River restoration
Fish Ecology
Water Framework Directive
Coastal Morphology
Hydrodynamics
Sediment Transport
Morphodynamic Forward Modelling
Coastal Engineering
geochemie
hydrologie
watermanagement
bodemmanagement
Coastal morphology
Coastal Engineering
Coastal Hazards
Flood Risk
Coastal Engineering
Coastal Structures
Hydraulic Engineering
water management
flood risk
landscape ecology
policy analysis
Water management
Climate adaptation
hydrology
sea level rise
Francois Clemens-Meyer
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
34
97
4,273
hydraulics
measuring techniques
asset management
wetland hydrology
peatlands
carbon dynamics
land subsidence
flood risk management
River Morphology
Fluvial Morphology
Morphodynamics
Mathematical Modelling
River Engineering
Bregje K. van Wesenbeeck
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
32
47
6,022
nature-based coastal defenses
coastal zone management
ecosystem-based adaptation
marshes and mangroves
Gualbert Oude Essink
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
32
81
4,294
hydrogeology
groundwater
freshwater
coastal aquifers
numerical modelling
Fine sediment transport and morphology in fluvial estuarine and marine environments
geologie
kustprocessen
geomorfologie
Inversion
Modeling
Hydrogeophysics
Near-surface geophysics
environmental assessments
indicators
benthic ecology
eutrophication
science-policy
Coastal changes
Coastal Morphology
Sandy Beaches
port sedimentation
numerical modelling of coastal morphodynamics
Environmental chemistry
risk assessment
ocean wave dynamics
climate and statistics
Suzanne Van Eekelen
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
23
40
2,714
geotechnical engineering
geosynthetics
ground improvement
Wouter van der Star
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
22
28
6,762
environmental biotechnology
geotechnical engineering
biogeochemistry
Catchment hydrology
hydrometeorology
climate change
big data
HPC & cloud
Jebbe Van Der Werf
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
22
34
1,775
Sediment Transport & Coastal Morphology
Coastal Engineering
Coastal and River Structures
Coastal Morphology
Miguel Dionisio Pires
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
22
26
2,211
Maarten van Ormondt
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
21
30
1,536
storm surge
waves
coastal hazards
Ecology
flood risk management
coastal zone management
river basin management
sea-level change
sedimentology
deltas
geomechanics
quaternary geology
Oceanography and Limnology
Coastal Dynamics
Water Quality
Ocean Colour Remote Sensing
Optical and Spatial Modelling
Frederiek Sperna Weiland
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
19
22
2,448
Water management
macrophytes
ecohydraulics
limnology
water quality and ecological modelling
Hydroinformatics
Earth Observation
Data Assimilation
Artificial Intelligence
Environmental engineering and ecology
systemecology
governance
limnology
sustainability
management
coastal development
eco-engineering
sediment toxicity
Geotechnical Engineering
Numerical and Constitutive Modeling in Geomechanics
Joachim Rozemeijer
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
18
27
1,791
Geographic Information Science
Exposure Assessment
Remote Sensing
Willem J. Van Verseveld
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
17
18
1,351
hillslope and watershed hydrology
flood forecasting
hydrological modelling
earth observations
environmental modeling
software design
visualization
machine learning
geotechniek
monitoring
dijken
Hendrik Reinhard Albert (Bert) Jagers
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
16
26
1,277
Foundation engineering
underground construction
soil-structure interaction
forensic engineering
observational method
hydrology
groundwater - surface water interaction
pathways
coastal groundwater
River Dynamics & Engineering
Hydraulics
Fluvial Geomorphology
Sediment Transport
Water Infrastructure
Thaiënne Agp Van Dijk
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
15
20
1,043
Marine Geology
bedform dynamics
glacial morphology and sedimentology
Geotechnics
Transportation
Optimization
flood risk management
resilience
hydrology
climate-related security risks
water management
building with nature
pilot projects
innovation
Margreet van Marle
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
14
15
3,166
Coastal hydrodynamics and morphology
Coastal Engineering
Nearshore Processes
coral reefs
coastal zone management
coastal adaptation
Coastal Engineering
Coastal Morphology
Morphodynamic Modelling
Sediment Transport
Building with Nature
coasts
climate change
sea level rise
deltas
adaptation
air-water flow
pipe flow
pressure transients
control systems
renewable energy
Adriaan Albert Markus
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
13
13
1,230
Geophysics
Geomechanics
Geo-Energy
Hydrogeology
Geomatics
Environmental studies
water quality and transport modelling
geotechniek
aardbevingen
verweking
offshore
Scenarios
Innovation
Climate Adaptation
Sustainable Development
Water Management
geotechnical engineering
numerical modelling
soil settlement
material point method
dike stablity
governance
delta governance
monitoring
governance arrangementen
implementation
Interoperability
integrated modelling
water management
innovation management
water management
aquatic ecology
water quality modelling monitoring management - Water Framework Directive
Lodewijk De Vet|P.L.M. de Vet
Deltares
Delft, Netherlands
Metrics
H-Index
i10 Index
Citation Counts
11
13
677
Morphodynamics
Estuaries & Coasts
Intertidal Flats
Field Measurements
Adaptation Strategies
Flood forecasting and early warning
Flood inundation modelling under uncertainty
Remote sensing
river morphodynamics
applied mathematics